MD Downloads: use <iron-list> to render download items

chrome/browser/resources/md_downloads/crisper.js

 // Copyright 2015 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 Polymer = {dom: 'shadow'};
 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 /**
@@ skipping 2335 matching lines @@
     removeAttribute: function(attr) {
       if (attr.toLowerCase() == 'disabled')
         this.disabled = false;
       else
         HTMLAnchorElement.prototype.removeAttribute.apply(this, arguments);
     },
   },
 
   extends: 'a',
 });
-// Copyright 2015 The Chromium Authors. All rights reserved.
-// Use of this source code is governed by a BSD-style license that can be
-// found in the LICENSE file.
-
-/** @typedef {{img: HTMLImageElement, url: string}} */
-var LoadIconRequest;
-
-cr.define('downloads', function() {
-  /**
-   * @param {number} maxAllowed The maximum number of simultaneous downloads
-   *     allowed.
-   * @constructor
-   */
-  function ThrottledIconLoader(maxAllowed) {
-    assert(maxAllowed > 0);
-
-    /** @private {number} */
-    this.maxAllowed_ = maxAllowed;
-
-    /** @private {!Array<!LoadIconRequest>} */
-    this.requests_ = [];
-  }
-
-  ThrottledIconLoader.prototype = {
-    /** @private {number} */
-    loading_: 0,
-
-    /**
-     * Load the provided |url| into |img.src| after appending ?scale=.
-     * @param {!HTMLImageElement} img An <img> to show the loaded image in.
-     * @param {string} url A remote image URL to load.
-     */
-    loadScaledIcon: function(img, url) {
-      var scaledUrl = url + '?scale=' + window.devicePixelRatio + 'x';
-      if (img.src == scaledUrl)
-        return;
-
-      this.requests_.push({img: img, url: scaledUrl});
-      this.loadNextIcon_();
-    },
-
-    /** @private */
-    loadNextIcon_: function() {
-      if (this.loading_ > this.maxAllowed_ || !this.requests_.length)
-        return;
-
-      var request = this.requests_.shift();
-      var img = request.img;
-
-      img.onabort = img.onerror = img.onload = function() {
-        this.loading_--;
-        this.loadNextIcon_();
-      }.bind(this);
-
-      this.loading_++;
-      img.src = request.url;
-    },
-  };
-
-  return {ThrottledIconLoader: ThrottledIconLoader};
-});
 // Copyright 2014 Google Inc. All rights reserved.
 //
 // Licensed under the Apache License, Version 2.0 (the "License");
 // you may not use this file except in compliance with the License.
 //     You may obtain a copy of the License at
 //
 // http://www.apache.org/licenses/LICENSE-2.0
 //
 // Unless required by applicable law or agreed to in writing, software
 // distributed under the License is distributed on an "AS IS" BASIS,
@@ skipping 573 matching lines @@
 debouncer.complete();
 }
 },
 cancelDebouncer: function (jobName) {
 var debouncer = this._debouncers[jobName];
 if (debouncer) {
 debouncer.stop();
 }
 }
 });
-Polymer.version = '1.1.4';
+Polymer.version = '1.1.5';
 Polymer.Base._addFeature({
 _registerFeatures: function () {
 this._prepIs();
 this._prepAttributes();
 this._prepBehaviors();
 this._prepConstructor();
 },
 _prepBehavior: function (b) {
 this._addHostAttributes(b.hostAttributes);
 },
@@ skipping 1856 matching lines @@
 name = key;
 } else {
 name = key.split('.');
 node = this.$[name[0]];
 name = name[1];
 }
 this.listen(node, name, listeners[key]);
 }
 },
 listen: function (node, eventName, methodName) {
-this._listen(node, eventName, this._createEventHandler(node, eventName, methodName));
+var handler = this._recallEventHandler(this, eventName, node, methodName);
+if (!handler) {
+handler = this._createEventHandler(node, eventName, methodName);
+}
+if (handler._listening) {
+return;
+}
+this._listen(node, eventName, handler);
+handler._listening = true;
 },
 _boundListenerKey: function (eventName, methodName) {
 return eventName + ':' + methodName;
 },
 _recordEventHandler: function (host, eventName, target, methodName, handler) {
 var hbl = host.__boundListeners;
 if (!hbl) {
 hbl = host.__boundListeners = new WeakMap();
 }
 var bl = hbl.get(target);
@@ skipping 18 matching lines @@
 },
 _createEventHandler: function (node, eventName, methodName) {
 var host = this;
 var handler = function (e) {
 if (host[methodName]) {
 host[methodName](e, e.detail);
 } else {
 host._warn(host._logf('_createEventHandler', 'listener method `' + methodName + '` not defined'));
 }
 };
+handler._listening = false;
 this._recordEventHandler(host, eventName, node, methodName, handler);
 return handler;
 },
 unlisten: function (node, eventName, methodName) {
 var handler = this._recallEventHandler(this, eventName, node, methodName);
 if (handler) {
 this._unlisten(node, eventName, handler);
+handler._listening = false;
 }
 },
 _listen: function (node, eventName, handler) {
 node.addEventListener(eventName, handler);
 },
 _unlisten: function (node, eventName, handler) {
 node.removeEventListener(eventName, handler);
 }
 });
 (function () {
@@ skipping 827 matching lines @@
 return l;
 },
 create: function (tag, props) {
 var elt = document.createElement(tag);
 if (props) {
 for (var n in props) {
 elt[n] = props[n];
 }
 }
 return elt;
+},
+isLightDescendant: function (node) {
+return this.contains(node) && Polymer.dom(this).getOwnerRoot() === Polymer.dom(node).getOwnerRoot();
+},
+isLocalDescendant: function (node) {
+return this.root === Polymer.dom(node).getOwnerRoot();
 }
 });
 Polymer.Bind = {
 prepareModel: function (model) {
 model._propertyEffects = {};
 model._bindListeners = [];
 Polymer.Base.mixin(model, this._modelApi);
 },
 _modelApi: {
 _notifyChange: function (property) {
@@ skipping 781 matching lines @@
 return ret;
 },
 unshift: function (path) {
 var array = this.get(path);
 var args = Array.prototype.slice.call(arguments, 1);
 var ret = array.unshift.apply(array, args);
 if (args.length) {
 this._notifySplice(array, path, 0, args.length, []);
 }
 return ret;
+},
+prepareModelNotifyPath: function (model) {
+this.mixin(model, {
+fire: Polymer.Base.fire,
+notifyPath: Polymer.Base.notifyPath,
+_EVENT_CHANGED: Polymer.Base._EVENT_CHANGED,
+_notifyPath: Polymer.Base._notifyPath,
+_pathEffector: Polymer.Base._pathEffector,
+_annotationPathEffect: Polymer.Base._annotationPathEffect,
+_complexObserverPathEffect: Polymer.Base._complexObserverPathEffect,
+_annotatedComputationPathEffect: Polymer.Base._annotatedComputationPathEffect,
+_computePathEffect: Polymer.Base._computePathEffect,
+_modelForPath: Polymer.Base._modelForPath,
+_pathMatchesEffect: Polymer.Base._pathMatchesEffect,
+_notifyBoundPaths: Polymer.Base._notifyBoundPaths
+});
 }
 });
 }());
 Polymer.Base._addFeature({
 resolveUrl: function (url) {
 var module = Polymer.DomModule.import(this.is);
 var root = '';
 if (module) {
 var assetPath = module.getAttribute('assetpath') || '';
 root = Polymer.ResolveUrl.resolveUrl(assetPath, module.ownerDocument.baseURI);
@@ skipping 1186 matching lines @@
 }
 });
 }
 });
 }());
 Polymer.Templatizer = {
 properties: { __hideTemplateChildren__: { observer: '_showHideChildren' } },
 _instanceProps: Polymer.nob,
 _parentPropPrefix: '_parent_',
 templatize: function (template) {
+this._templatized = template;
 if (!template._content) {
 template._content = template.content;
 }
 if (template._content._ctor) {
 this.ctor = template._content._ctor;
 this._prepParentProperties(this.ctor.prototype, template);
 return;
 }
 var archetype = Object.create(Polymer.Base);
 this._customPrepAnnotations(archetype, template);
+this._prepParentProperties(archetype, template);
 archetype._prepEffects();
 this._customPrepEffects(archetype);
 archetype._prepBehaviors();
 archetype._prepBindings();
-this._prepParentProperties(archetype, template);
 archetype._notifyPath = this._notifyPathImpl;
 archetype._scopeElementClass = this._scopeElementClassImpl;
 archetype.listen = this._listenImpl;
 archetype._showHideChildren = this._showHideChildrenImpl;
 var _constructor = this._constructorImpl;
 var ctor = function TemplateInstance(model, host) {
 _constructor.call(this, model, host);
 };
 ctor.prototype = archetype;
 archetype.constructor = ctor;
@@ skipping 62 matching lines @@
 if (this._forwardParentProp && parentProps) {
 var proto = archetype._parentPropProto;
 var prop;
 if (!proto) {
 for (prop in this._instanceProps) {
 delete parentProps[prop];
 }
 proto = archetype._parentPropProto = Object.create(null);
 if (template != this) {
 Polymer.Bind.prepareModel(proto);
+Polymer.Base.prepareModelNotifyPath(proto);
 }
 for (prop in parentProps) {
 var parentProp = this._parentPropPrefix + prop;
 var effects = [
 {
 kind: 'function',
 effect: this._createForwardPropEffector(prop)
 },
 { kind: 'notify' }
 ];
 Polymer.Bind._createAccessors(proto, parentProp, effects);
 }
 }
 if (template != this) {
 Polymer.Bind.prepareInstance(template);
 template._forwardParentProp = this._forwardParentProp.bind(this);
 }
 this._extendTemplate(template, proto);
+template._pathEffector = this._pathEffectorImpl.bind(this);
 }
 },
 _createForwardPropEffector: function (prop) {
 return function (source, value) {
 this._forwardParentProp(prop, value);
 };
 },
 _createHostPropEffector: function (prop) {
 var prefix = this._parentPropPrefix;
 return function (source, value) {
-this.dataHost[prefix + prop] = value;
+this.dataHost._templatized[prefix + prop] = value;
 };
 },
 _createInstancePropEffector: function (prop) {
 return function (source, value, old, fromAbove) {
 if (!fromAbove) {
 this.dataHost._forwardInstanceProp(this, prop, value);
 }
 };
 },
 _extendTemplate: function (template, proto) {
@@ skipping 11 matching lines @@
 _forwardInstancePath: function (inst, path, value) {
 },
 _forwardInstanceProp: function (inst, prop, value) {
 },
 _notifyPathImpl: function (path, value) {
 var dataHost = this.dataHost;
 var dot = path.indexOf('.');
 var root = dot < 0 ? path : path.slice(0, dot);
 dataHost._forwardInstancePath.call(dataHost, this, path, value);
 if (root in dataHost._parentProps) {
-dataHost.notifyPath(dataHost._parentPropPrefix + path, value);
+dataHost._templatized.notifyPath(dataHost._parentPropPrefix + path, value);
 }
 },
-_pathEffector: function (path, value, fromAbove) {
+_pathEffectorImpl: function (path, value, fromAbove) {
 if (this._forwardParentPath) {
 if (path.indexOf(this._parentPropPrefix) === 0) {
-this._forwardParentPath(path.substring(8), value);
+var subPath = path.substring(this._parentPropPrefix.length);
+this._forwardParentPath(subPath, value);
 }
 }
-Polymer.Base._pathEffector.apply(this, arguments);
+Polymer.Base._pathEffector.call(this._templatized, path, value, fromAbove);
 },
 _constructorImpl: function (model, host) {
 this._rootDataHost = host._getRootDataHost();
 this._setupConfigure(model);
 this._pushHost(host);
 this.root = this.instanceTemplate(this._template);
 this.root.__noContent = !this._notes._hasContent;
 this.root.__styleScoped = true;
 this._popHost();
 this._marshalAnnotatedNodes();
@@ skipping 22 matching lines @@
 },
 _scopeElementClassImpl: function (node, value) {
 var host = this._rootDataHost;
 if (host) {
 return host._scopeElementClass(node, value);
 }
 },
 stamp: function (model) {
 model = model || {};
 if (this._parentProps) {
+var templatized = this._templatized;
 for (var prop in this._parentProps) {
-model[prop] = this[this._parentPropPrefix + prop];
+model[prop] = templatized[this._parentPropPrefix + prop];
 }
 }
 return new this.ctor(model, this);
 },
 modelForElement: function (el) {
 var model;
 while (el) {
 if (model = el._templateInstance) {
 if (model.dataHost != this) {
 el = model.dataHost;
@@ skipping 587 matching lines @@
 select: function (item) {
 var icol = Polymer.Collection.get(this.items);
 var key = icol.getKey(item);
 if (this.multi) {
 if (this.isSelected(item)) {
 if (this.toggle) {
 this.deselect(item);
 }
 } else {
 this.push('selected', item);
-skey = this._selectedColl.getKey(item);
+var skey = this._selectedColl.getKey(item);
 this.linkPaths('selected.' + skey, 'items.' + key);
 }
 } else {
 if (this.toggle && item == this.selected) {
 this.deselect();
 } else {
 this.selected = item;
 this.selectedItem = item;
 this.linkPaths('selected', 'items.' + key);
 this.linkPaths('selectedItem', 'items.' + key);
@@ skipping 148 matching lines @@
 this._prepBehaviors();
 this._prepConfigure();
 this._prepBindings();
 Polymer.Base._initFeatures.call(this);
 this._children = Array.prototype.slice.call(this.root.childNodes);
 }
 this._insertChildren();
 this.fire('dom-change');
 }
 });
+/**
+   * `IronResizableBehavior` is a behavior that can be used in Polymer elements to
+   * coordinate the flow of resize events between "resizers" (elements that control the
+   * size or hidden state of their children) and "resizables" (elements that need to be
+   * notified when they are resized or un-hidden by their parents in order to take
+   * action on their new measurements).
+   * Elements that perform measurement should add the `IronResizableBehavior` behavior to
+   * their element definition and listen for the `iron-resize` event on themselves.
+   * This event will be fired when they become showing after having been hidden,
+   * when they are resized explicitly by another resizable, or when the window has been
+   * resized.
+   * Note, the `iron-resize` event is non-bubbling.
+   *
+   * @polymerBehavior Polymer.IronResizableBehavior
+   * @demo demo/index.html
+   **/
+  Polymer.IronResizableBehavior = {
+    properties: {
+      /**
+       * The closest ancestor element that implements `IronResizableBehavior`.
+       */
+      _parentResizable: {
+        type: Object,
+        observer: '_parentResizableChanged'
+      },
+
+      /**
+       * True if this element is currently notifying its descedant elements of
+       * resize.
+       */
+      _notifyingDescendant: {
+        type: Boolean,
+        value: false
+      }
+    },
+
+    listeners: {
+      'iron-request-resize-notifications': '_onIronRequestResizeNotifications'
+    },
+
+    created: function() {
+      // We don't really need property effects on these, and also we want them
+      // to be created before the `_parentResizable` observer fires:
+      this._interestedResizables = [];
+      this._boundNotifyResize = this.notifyResize.bind(this);
+    },
+
+    attached: function() {
+      this.fire('iron-request-resize-notifications', null, {
+        node: this,
+        bubbles: true,
+        cancelable: true
+      });
+
+      if (!this._parentResizable) {
+        window.addEventListener('resize', this._boundNotifyResize);
+        this.notifyResize();
+      }
+    },
+
+    detached: function() {
+      if (this._parentResizable) {
+        this._parentResizable.stopResizeNotificationsFor(this);
+      } else {
+        window.removeEventListener('resize', this._boundNotifyResize);
+      }
+
+      this._parentResizable = null;
+    },
+
+    /**
+     * Can be called to manually notify a resizable and its descendant
+     * resizables of a resize change.
+     */
+    notifyResize: function() {
+      if (!this.isAttached) {
+        return;
+      }
+
+      this._interestedResizables.forEach(function(resizable) {
+        if (this.resizerShouldNotify(resizable)) {
+          this._notifyDescendant(resizable);
+        }
+      }, this);
+
+      this._fireResize();
+    },
+
+    /**
+     * Used to assign the closest resizable ancestor to this resizable
+     * if the ancestor detects a request for notifications.
+     */
+    assignParentResizable: function(parentResizable) {
+      this._parentResizable = parentResizable;
+    },
+
+    /**
+     * Used to remove a resizable descendant from the list of descendants
+     * that should be notified of a resize change.
+     */
+    stopResizeNotificationsFor: function(target) {
+      var index = this._interestedResizables.indexOf(target);
+
+      if (index > -1) {
+        this._interestedResizables.splice(index, 1);
+        this.unlisten(target, 'iron-resize', '_onDescendantIronResize');
+      }
+    },
+
+    /**
+     * This method can be overridden to filter nested elements that should or
+     * should not be notified by the current element. Return true if an element
+     * should be notified, or false if it should not be notified.
+     *
+     * @param {HTMLElement} element A candidate descendant element that
+     * implements `IronResizableBehavior`.
+     * @return {boolean} True if the `element` should be notified of resize.
+     */
+    resizerShouldNotify: function(element) { return true; },
+
+    _onDescendantIronResize: function(event) {
+      if (this._notifyingDescendant) {
+        event.stopPropagation();
+        return;
+      }
+
+      // NOTE(cdata): In ShadowDOM, event retargetting makes echoing of the
+      // otherwise non-bubbling event "just work." We do it manually here for
+      // the case where Polymer is not using shadow roots for whatever reason:
+      if (!Polymer.Settings.useShadow) {
+        this._fireResize();
+      }
+    },
+
+    _fireResize: function() {
+      this.fire('iron-resize', null, {
+        node: this,
+        bubbles: false
+      });
+    },
+
+    _onIronRequestResizeNotifications: function(event) {
+      var target = event.path ? event.path[0] : event.target;
+
+      if (target === this) {
+        return;
+      }
+
+      if (this._interestedResizables.indexOf(target) === -1) {
+        this._interestedResizables.push(target);
+        this.listen(target, 'iron-resize', '_onDescendantIronResize');
+      }
+
+      target.assignParentResizable(this);
+      this._notifyDescendant(target);
+
+      event.stopPropagation();
+    },
+
+    _parentResizableChanged: function(parentResizable) {
+      if (parentResizable) {
+        window.removeEventListener('resize', this._boundNotifyResize);
+      }
+    },
+
+    _notifyDescendant: function(descendant) {
+      // NOTE(cdata): In IE10, attached is fired on children first, so it's
+      // important not to notify them if the parent is not attached yet (or
+      // else they will get redundantly notified when the parent attaches).
+      if (!this.isAttached) {
+        return;
+      }
+
+      this._notifyingDescendant = true;
+      descendant.notifyResize();
+      this._notifyingDescendant = false;
+    }
+  };
+(function() {
+
+  var IOS = navigator.userAgent.match(/iP(?:hone|ad;(?: U;)? CPU) OS (\d+)/);
+  var IOS_TOUCH_SCROLLING = IOS && IOS[1] >= 8;
+  var DEFAULT_PHYSICAL_COUNT = 20;
+  var MAX_PHYSICAL_COUNT = 500;
+
+  Polymer({
+
+    is: 'iron-list',
+
+    properties: {
+
+      /**
+       * An array containing items determining how many instances of the template
+       * to stamp and that that each template instance should bind to.
+       */
+      items: {
+        type: Array
+      },
+
+      /**
+       * The name of the variable to add to the binding scope for the array
+       * element associated with a given template instance.
+       */
+      as: {
+        type: String,
+        value: 'item'
+      },
+
+      /**
+       * The name of the variable to add to the binding scope with the index
+       * for the row.  If `sort` is provided, the index will reflect the
+       * sorted order (rather than the original array order).
+       */
+      indexAs: {
+        type: String,
+        value: 'index'
+      },
+
+      /**
+       * The name of the variable to add to the binding scope to indicate
+       * if the row is selected.
+       */
+      selectedAs: {
+        type: String,
+        value: 'selected'
+      },
+
+      /**
+       * When true, tapping a row will select the item, placing its data model
+       * in the set of selected items retrievable via the selection property.
+       *
+       * Note that tapping focusable elements within the list item will not
+       * result in selection, since they are presumed to have their * own action.
+       */
+      selectionEnabled: {
+        type: Boolean,
+        value: false
+      },
+
+      /**
+       * When `multiSelection` is false, this is the currently selected item, or `null`
+       * if no item is selected.
+       */
+      selectedItem: {
+        type: Object,
+        notify: true
+      },
+
+      /**
+       * When `multiSelection` is true, this is an array that contains the selected items.
+       */
+      selectedItems: {
+        type: Object,
+        notify: true
+      },
+
+      /**
+       * When `true`, multiple items may be selected at once (in this case,
+       * `selected` is an array of currently selected items).  When `false`,
+       * only one item may be selected at a time.
+       */
+      multiSelection: {
+        type: Boolean,
+        value: false
+      }
+    },
+
+    observers: [
+      '_itemsChanged(items.*)',
+      '_selectionEnabledChanged(selectionEnabled)',
+      '_multiSelectionChanged(multiSelection)'
+    ],
+
+    behaviors: [
+      Polymer.Templatizer,
+      Polymer.IronResizableBehavior
+    ],
+
+    listeners: {
+      'iron-resize': '_resizeHandler'
+    },
+
+    /**
+     * The ratio of hidden tiles that should remain in the scroll direction.
+     * Recommended value ~0.5, so it will distribute tiles evely in both directions.
+     */
+    _ratio: 0.5,
+
+    /**
+     * The element that controls the scroll
+     * @type {?Element}
+     */
+    _scroller: null,
+
+    /**
+     * The padding-top value of the `scroller` element
+     */
+    _scrollerPaddingTop: 0,
+
+    /**
+     * This value is the same as `scrollTop`.
+     */
+    _scrollPosition: 0,
+
+    /**
+     * The number of tiles in the DOM.
+     */
+    _physicalCount: 0,
+
+    /**
+     * The k-th tile that is at the top of the scrolling list.
+     */
+    _physicalStart: 0,
+
+    /**
+     * The k-th tile that is at the bottom of the scrolling list.
+     */
+    _physicalEnd: 0,
+
+    /**
+     * The sum of the heights of all the tiles in the DOM.
+     */
+    _physicalSize: 0,
+
+    /**
+     * The average `offsetHeight` of the tiles observed till now.
+     */
+    _physicalAverage: 0,
+
+    /**
+     * The number of tiles which `offsetHeight` > 0 observed until now.
+     */
+    _physicalAverageCount: 0,
+
+    /**
+     * The Y position of the item rendered in the `_physicalStart`
+     * tile relative to the scrolling list.
+     */
+    _physicalTop: 0,
+
+    /**
+     * The number of items in the list.
+     */
+    _virtualCount: 0,
+
+    /**
+     * The n-th item rendered in the `_physicalStart` tile.
+     */
+    _virtualStartVal: 0,
+
+    /**
+     * A map between an item key and its physical item index
+     */
+    _physicalIndexForKey: null,
+
+    /**
+     * The estimated scroll height based on `_physicalAverage`
+     */
+    _estScrollHeight: 0,
+
+    /**
+     * The scroll height of the dom node
+     */
+    _scrollHeight: 0,
+
+    /**
+     * The size of the viewport
+     */
+    _viewportSize: 0,
+
+    /**
+     * An array of DOM nodes that are currently in the tree
+     * @type {?Array<!TemplatizerNode>}
+     */
+    _physicalItems: null,
+
+    /**
+     * An array of heights for each item in `_physicalItems`
+     * @type {?Array<number>}
+     */
+    _physicalSizes: null,
+
+    /**
+     * A cached value for the visible index.
+     * See `firstVisibleIndex`
+     * @type {?number}
+     */
+    _firstVisibleIndexVal: null,
+
+    /**
+     * A Polymer collection for the items.
+     * @type {?Polymer.Collection}
+     */
+    _collection: null,
+
+    /**
+     * True if the current item list was rendered for the first time
+     * after attached.
+     */
+    _itemsRendered: false,
+
+    /**
+     * The bottom of the physical content.
+     */
+    get _physicalBottom() {
+      return this._physicalTop + this._physicalSize;
+    },
+
+    /**
+     * The n-th item rendered in the last physical item.
+     */
+    get _virtualEnd() {
+      return this._virtualStartVal + this._physicalCount - 1;
+    },
+
+    /**
+     * The lowest n-th value for an item such that it can be rendered in `_physicalStart`.
+     */
+    _minVirtualStart: 0,
+
+    /**
+     * The largest n-th value for an item such that it can be rendered in `_physicalStart`.
+     */
+    get _maxVirtualStart() {
+      return this._virtualCount < this._physicalCount ?
+          this._virtualCount : this._virtualCount - this._physicalCount;
+    },
+
+    /**
+     * The height of the physical content that isn't on the screen.
+     */
+    get _hiddenContentSize() {
+      return this._physicalSize - this._viewportSize;
+    },
+
+    /**
+     * The maximum scroll top value.
+     */
+    get _maxScrollTop() {
+      return this._estScrollHeight - this._viewportSize;
+    },
+
+    /**
+     * Sets the n-th item rendered in `_physicalStart`
+     */
+    set _virtualStart(val) {
+      // clamp the value so that _minVirtualStart <= val <= _maxVirtualStart
+      this._virtualStartVal = Math.min(this._maxVirtualStart, Math.max(this._minVirtualStart, val));
+      this._physicalStart = this._virtualStartVal % this._physicalCount;
+      this._physicalEnd = (this._physicalStart + this._physicalCount - 1) % this._physicalCount;
+    },
+
+    /**
+     * Gets the n-th item rendered in `_physicalStart`
+     */
+    get _virtualStart() {
+      return this._virtualStartVal;
+    },
+
+    /**
+     * An optimal physical size such that we will have enough physical items
+     * to fill up the viewport and recycle when the user scrolls.
+     *
+     * This default value assumes that we will at least have the equivalent
+     * to a viewport of physical items above and below the user's viewport.
+     */
+    get _optPhysicalSize() {
+      return this._viewportSize * 3;
+    },
+
+   /**
+    * True if the current list is visible.
+    */
+    get _isVisible() {
+      return this._scroller && Boolean(this._scroller.offsetWidth || this._scroller.offsetHeight);
+    },
+
+    /**
+     * Gets the first visible item in the viewport.
+     *
+     * @type {number}
+     */
+    get firstVisibleIndex() {
+      var physicalOffset;
+
+      if (this._firstVisibleIndexVal === null) {
+        physicalOffset = this._physicalTop;
+
+        this._firstVisibleIndexVal = this._iterateItems(
+          function(pidx, vidx) {
+            physicalOffset += this._physicalSizes[pidx];
+
+            if (physicalOffset > this._scrollPosition) {
+              return vidx;
+            }
+          }) || 0;
+      }
+
+      return this._firstVisibleIndexVal;
+    },
+
+    ready: function() {
+      if (IOS_TOUCH_SCROLLING) {
+        this._scrollListener = function() {
+          requestAnimationFrame(this._scrollHandler.bind(this));
+        }.bind(this);
+      } else {
+        this._scrollListener = this._scrollHandler.bind(this);
+      }
+    },
+
+    /**
+     * When the element has been attached to the DOM tree.
+     */
+    attached: function() {
+      // delegate to the parent's scroller
+      // e.g. paper-scroll-header-panel
+      var el = Polymer.dom(this);
+
+      var parentNode = /** @type {?{scroller: ?Element}} */ (el.parentNode);
+      if (parentNode && parentNode.scroller) {
+        this._scroller = parentNode.scroller;
+      } else {
+        this._scroller = this;
+        this.classList.add('has-scroller');
+      }
+
+      if (IOS_TOUCH_SCROLLING) {
+        this._scroller.style.webkitOverflowScrolling = 'touch';
+      }
+
+      this._scroller.addEventListener('scroll', this._scrollListener);
+
+      this.updateViewportBoundaries();
+      this._render();
+    },
+
+    /**
+     * When the element has been removed from the DOM tree.
+     */
+    detached: function() {
+      this._itemsRendered = false;
+      if (this._scroller) {
+        this._scroller.removeEventListener('scroll', this._scrollListener);
+      }
+    },
+
+    /**
+     * Invoke this method if you dynamically update the viewport's
+     * size or CSS padding.
+     *
+     * @method updateViewportBoundaries
+     */
+    updateViewportBoundaries: function() {
+      var scrollerStyle = window.getComputedStyle(this._scroller);
+      this._scrollerPaddingTop = parseInt(scrollerStyle['padding-top'], 10);
+      this._viewportSize = this._scroller.offsetHeight;
+    },
+
+    /**
+     * Update the models, the position of the
+     * items in the viewport and recycle tiles as needed.
+     */
+    _refresh: function() {
+      var SCROLL_DIRECTION_UP = -1;
+      var SCROLL_DIRECTION_DOWN = 1;
+      var SCROLL_DIRECTION_NONE = 0;
+
+      // clamp the `scrollTop` value
+      // IE 10|11 scrollTop may go above `_maxScrollTop`
+      // iOS `scrollTop` may go below 0 and above `_maxScrollTop`
+      var scrollTop = Math.max(0, Math.min(this._maxScrollTop, this._scroller.scrollTop));
+
+      var tileHeight, kth, recycledTileSet;
+      var ratio = this._ratio;
+      var delta = scrollTop - this._scrollPosition;
+      var direction = SCROLL_DIRECTION_NONE;
+      var recycledTiles = 0;
+      var hiddenContentSize = this._hiddenContentSize;
+      var currentRatio = ratio;
+      var movingUp = [];
+
+      // track the last `scrollTop`
+      this._scrollPosition = scrollTop;
+
+      // clear cached visible index
+      this._firstVisibleIndexVal = null;
+
+      // random access
+      if (Math.abs(delta) > this._physicalSize) {
+        this._physicalTop += delta;
+        direction = SCROLL_DIRECTION_NONE;
+        recycledTiles =  Math.round(delta / this._physicalAverage);
+      }
+      // scroll up
+      else if (delta < 0) {
+        var topSpace = scrollTop - this._physicalTop;
+        var virtualStart = this._virtualStart;
+
+        direction = SCROLL_DIRECTION_UP;
+        recycledTileSet = [];
+
+        kth = this._physicalEnd;
+        currentRatio = topSpace / hiddenContentSize;
+
+        // move tiles from bottom to top
+        while (
+            // approximate `currentRatio` to `ratio`
+            currentRatio < ratio &&
+            // recycle less physical items than the total
+            recycledTiles < this._physicalCount &&
+            // ensure that these recycled tiles are needed
+            virtualStart - recycledTiles > 0
+        ) {
+
+          tileHeight = this._physicalSizes[kth] || this._physicalAverage;
+          currentRatio += tileHeight / hiddenContentSize;
+
+          recycledTileSet.push(kth);
+          recycledTiles++;
+          kth = (kth === 0) ? this._physicalCount - 1 : kth - 1;
+        }
+
+        movingUp = recycledTileSet;
+        recycledTiles = -recycledTiles;
+
+      }
+      // scroll down
+      else if (delta > 0) {
+        var bottomSpace = this._physicalBottom - (scrollTop + this._viewportSize);
+        var virtualEnd = this._virtualEnd;
+        var lastVirtualItemIndex = this._virtualCount-1;
+
+        direction = SCROLL_DIRECTION_DOWN;
+        recycledTileSet = [];
+
+        kth = this._physicalStart;
+        currentRatio = bottomSpace / hiddenContentSize;
+
+        // move tiles from top to bottom
+        while (
+            // approximate `currentRatio` to `ratio`
+            currentRatio < ratio &&
+            // recycle less physical items than the total
+            recycledTiles < this._physicalCount &&
+            // ensure that these recycled tiles are needed
+            virtualEnd + recycledTiles < lastVirtualItemIndex
+          ) {
+
+          tileHeight = this._physicalSizes[kth] || this._physicalAverage;
+          currentRatio += tileHeight / hiddenContentSize;
+
+          this._physicalTop += tileHeight;
+          recycledTileSet.push(kth);
+          recycledTiles++;
+          kth = (kth + 1) % this._physicalCount;
+        }
+      }
+
+      if (recycledTiles !== 0) {
+        this._virtualStart = this._virtualStart + recycledTiles;
+        this._update(recycledTileSet, movingUp);
+      }
+    },
+
+    /**
+     * Update the list of items, starting from the `_virtualStartVal` item.
+     * @param {!Array<number>=} itemSet
+     * @param {!Array<number>=} movingUp
+     */
+    _update: function(itemSet, movingUp) {
+      // update models
+      this._assignModels(itemSet);
+
+      // measure heights
+      this._updateMetrics(itemSet);
+
+      // adjust offset after measuring
+      if (movingUp) {
+        while (movingUp.length) {
+          this._physicalTop -= this._physicalSizes[movingUp.pop()];
+        }
+      }
+      // update the position of the items
+      this._positionItems();
+
+      // set the scroller size
+      this._updateScrollerSize();
+
+      // increase the pool of physical items if needed
+      if (this._increasePoolIfNeeded()) {
+        // set models to the new items
+        this.async(this._update);
+      }
+    },
+
+    /**
+     * Creates a pool of DOM elements and attaches them to the local dom.
+     */
+    _createPool: function(size) {
+      var physicalItems = new Array(size);
+
+      this._ensureTemplatized();
+
+      for (var i = 0; i < size; i++) {
+        var inst = this.stamp(null);
+
+        // First element child is item; Safari doesn't support children[0]
+        // on a doc fragment
+        physicalItems[i] = inst.root.querySelector('*');
+        Polymer.dom(this).appendChild(inst.root);
+      }
+
+      return physicalItems;
+    },
+
+    /**
+     * Increases the pool size. That is, the physical items in the DOM.
+     * This function will allocate additional physical items
+     * (limited by `MAX_PHYSICAL_COUNT`) if the content size is shorter than
+     * `_optPhysicalSize`
+     *
+     * @return boolean
+     */
+    _increasePoolIfNeeded: function() {
+      if (this._physicalSize >= this._optPhysicalSize || this._physicalAverage === 0) {
+        return false;
+      }
+
+      // the estimated number of physical items that we will need to reach
+      // the cap established by `_optPhysicalSize`.
+      var missingItems = Math.round(
+          (this._optPhysicalSize - this._physicalSize) * 1.2 / this._physicalAverage
+        );
+
+      // limit the size
+      var nextPhysicalCount = Math.min(
+          this._physicalCount + missingItems,
+          this._virtualCount,
+          MAX_PHYSICAL_COUNT
+        );
+
+      var prevPhysicalCount = this._physicalCount;
+      var delta = nextPhysicalCount - prevPhysicalCount;
+
+      if (delta <= 0) {
+        return false;
+      }
+
+      var newPhysicalItems = this._createPool(delta);
+      var emptyArray = new Array(delta);
+
+      [].push.apply(this._physicalItems, newPhysicalItems);
+      [].push.apply(this._physicalSizes, emptyArray);
+
+      this._physicalCount = prevPhysicalCount + delta;
+ 
+      return true;
+    },
+
+    /**
+     * Render a new list of items. This method does exactly the same as `update`,
+     * but it also ensures that only one `update` cycle is created.
+     */
+    _render: function() {
+      var requiresUpdate = this._virtualCount > 0 || this._physicalCount > 0;
+
+      if (this.isAttached && !this._itemsRendered && this._isVisible && requiresUpdate)  {
+        this._update();
+        this._itemsRendered = true;
+      }
+    },
+
+    /**
+     * Templetizes the user template.
+     */
+    _ensureTemplatized: function() {
+      if (!this.ctor) {
+        // Template instance props that should be excluded from forwarding
+        var props = {};
+
+        props.__key__ = true;
+        props[this.as] = true;
+        props[this.indexAs] = true;
+        props[this.selectedAs] = true;
+
+        this._instanceProps = props;
+        this._userTemplate = Polymer.dom(this).querySelector('template');
+
+        if (this._userTemplate) {
+          this.templatize(this._userTemplate);
+        } else {
+          console.warn('iron-list requires a template to be provided in light-dom');
+        }
+      }
+    },
+
+    /**
+     * Implements extension point from Templatizer mixin.
+     */
+    _getStampedChildren: function() {
+      return this._physicalItems;
+    },
+
+    /**
+     * Implements extension point from Templatizer
+     * Called as a side effect of a template instance path change, responsible
+     * for notifying items.<key-for-instance>.<path> change up to host.
+     */
+    _forwardInstancePath: function(inst, path, value) {
+      if (path.indexOf(this.as + '.') === 0) {
+        this.notifyPath('items.' + inst.__key__ + '.' +
+          path.slice(this.as.length + 1), value);
+      }
+    },
+
+    /**
+     * Implements extension point from Templatizer mixin
+     * Called as side-effect of a host property change, responsible for
+     * notifying parent path change on each row.
+     */
+    _forwardParentProp: function(prop, value) {
+      if (this._physicalItems) {
+        this._physicalItems.forEach(function(item) {
+          item._templateInstance[prop] = value;
+        }, this);
+      }
+    },
+
+    /**
+     * Implements extension point from Templatizer
+     * Called as side-effect of a host path change, responsible for
+     * notifying parent.<path> path change on each row.
+     */
+    _forwardParentPath: function(path, value) {
+      if (this._physicalItems) {
+        this._physicalItems.forEach(function(item) {
+          item._templateInstance.notifyPath(path, value, true);
+        }, this);
+      }
+    },
+
+    /**
+     * Called as a side effect of a host items.<key>.<path> path change,
+     * responsible for notifying item.<path> changes to row for key.
+     */
+    _forwardItemPath: function(path, value) {
+      if (this._physicalIndexForKey) {
+        var dot = path.indexOf('.');
+        var key = path.substring(0, dot < 0 ? path.length : dot);
+        var idx = this._physicalIndexForKey[key];
+        var row = this._physicalItems[idx];
+        if (row) {
+          var inst = row._templateInstance;
+          if (dot >= 0) {
+            path = this.as + '.' + path.substring(dot+1);
+            inst.notifyPath(path, value, true);
+          } else {
+            inst[this.as] = value;
+          }
+        }
+      }
+    },
+
+    /**
+     * Called when the items have changed. That is, ressignments
+     * to `items`, splices or updates to a single item.
+     */
+    _itemsChanged: function(change) {
+      if (change.path === 'items') {
+        // render the new set
+        this._itemsRendered = false;
+
+        // update the whole set
+        this._virtualStartVal = 0;
+        this._physicalTop = 0;
+        this._virtualCount = this.items ? this.items.length : 0;
+        this._collection = this.items ? Polymer.Collection.get(this.items) : null;
+        this._physicalIndexForKey = {};
+
+        // scroll to the top
+        this._resetScrollPosition(0);
+
+        // create the initial physical items
+        if (!this._physicalItems) {
+          this._physicalCount = Math.max(1, Math.min(DEFAULT_PHYSICAL_COUNT, this._virtualCount));
+          this._physicalItems = this._createPool(this._physicalCount);
+          this._physicalSizes = new Array(this._physicalCount);
+        }
+
+        this.debounce('refresh', this._render);
+
+      } else if (change.path === 'items.splices') {
+        // render the new set
+        this._itemsRendered = false;
+
+        this._adjustVirtualIndex(change.value.indexSplices);
+        this._virtualCount = this.items ? this.items.length : 0;
+
+        this.debounce('refresh', this._render);
+
+      } else {
+        // update a single item
+        this._forwardItemPath(change.path.split('.').slice(1).join('.'), change.value);
+      }
+    },
+
+    /**
+     * @param {!Array<!PolymerSplice>} splices
+     */
+    _adjustVirtualIndex: function(splices) {
+      var i, splice, idx;
+
+      for (i = 0; i < splices.length; i++) {
+        splice = splices[i];
+
+        // deselect removed items
+        splice.removed.forEach(this.$.selector.deselect, this.$.selector);
+
+        idx = splice.index;
+        // We only need to care about changes happening above the current position
+        if (idx >= this._virtualStartVal) {
+          break;
+        }
+
+        this._virtualStart = this._virtualStart +
+            Math.max(splice.addedCount - splice.removed.length, idx - this._virtualStartVal);
+      }
+    },
+
+    _scrollHandler: function() {
+      this._refresh();
+    },
+
+    /**
+     * Executes a provided function per every physical index in `itemSet`
+     * `itemSet` default value is equivalent to the entire set of physical indexes.
+     * 
+     * @param {!function(number, number)} fn
+     * @param {!Array<number>=} itemSet
+     */
+    _iterateItems: function(fn, itemSet) {
+      var pidx, vidx, rtn, i;
+
+      if (arguments.length === 2 && itemSet) {
+        for (i = 0; i < itemSet.length; i++) {
+          pidx = itemSet[i];
+          if (pidx >= this._physicalStart) {
+            vidx = this._virtualStartVal + (pidx - this._physicalStart);
+          } else {
+            vidx = this._virtualStartVal + (this._physicalCount - this._physicalStart) + pidx;
+          }
+          if ((rtn = fn.call(this, pidx, vidx)) != null) {
+            return rtn;
+          }
+        }
+      } else {
+        pidx = this._physicalStart;
+        vidx = this._virtualStartVal;
+
+        for (; pidx < this._physicalCount; pidx++, vidx++) {
+          if ((rtn = fn.call(this, pidx, vidx)) != null) {
+            return rtn;
+          }
+        }
+
+        pidx = 0;
+
+        for (; pidx < this._physicalStart; pidx++, vidx++) {
+          if ((rtn = fn.call(this, pidx, vidx)) != null) {
+            return rtn;
+          }
+        }
+      }
+    },
+
+    /**
+     * Assigns the data models to a given set of items.
+     * @param {!Array<number>=} itemSet
+     */
+    _assignModels: function(itemSet) {
+      this._iterateItems(function(pidx, vidx) {
+        var el = this._physicalItems[pidx];
+        var inst = el._templateInstance;
+        var item = this.items && this.items[vidx];
+
+        if (item) {
+          inst[this.as] = item;
+          inst.__key__ = this._collection.getKey(item);
+          inst[this.selectedAs] =
+            /** @type {!ArraySelectorElement} */ (this.$.selector).isSelected(item);
+          inst[this.indexAs] = vidx;
+          el.removeAttribute('hidden');
+          this._physicalIndexForKey[inst.__key__] = pidx;
+        } else {
+          inst.__key__ = null;
+          el.setAttribute('hidden', '');
+        }
+
+      }, itemSet);
+    },
+
+    /**
+     * Updates the height for a given set of items.
+     *
+     * @param {!Array<number>=} itemSet
+     */
+     _updateMetrics: function(itemSet) {
+      var newPhysicalSize = 0;
+      var oldPhysicalSize = 0;
+      var prevAvgCount = this._physicalAverageCount;
+      var prevPhysicalAvg = this._physicalAverage;
+      // Make sure we distributed all the physical items
+      // so we can measure them
+      Polymer.dom.flush();
+
+      this._iterateItems(function(pidx, vidx) {
+        oldPhysicalSize += this._physicalSizes[pidx] || 0;
+        this._physicalSizes[pidx] = this._physicalItems[pidx].offsetHeight;
+        newPhysicalSize += this._physicalSizes[pidx];
+        this._physicalAverageCount += this._physicalSizes[pidx] ? 1 : 0;
+      }, itemSet);
+
+      this._physicalSize = this._physicalSize + newPhysicalSize - oldPhysicalSize;
+      this._viewportSize = this._scroller.offsetHeight;
+
+      // update the average if we measured something
+      if (this._physicalAverageCount !== prevAvgCount) {
+        this._physicalAverage = Math.round(
+            ((prevPhysicalAvg * prevAvgCount) + newPhysicalSize) /
+            this._physicalAverageCount);
+      }
+    },
+
+    /**
+     * Updates the position of the physical items.
+     */
+    _positionItems: function() {
+      this._adjustScrollPosition();
+
+      var y = this._physicalTop;
+
+      this._iterateItems(function(pidx) {
+
+        this.transform('translate3d(0, ' + y + 'px, 0)', this._physicalItems[pidx]);
+        y += this._physicalSizes[pidx];
+
+      });
+    },
+
+    /**
+     * Adjusts the scroll position when it was overestimated.
+     */
+    _adjustScrollPosition: function() {
+      var deltaHeight = this._virtualStartVal === 0 ? this._physicalTop :
+          Math.min(this._scrollPosition + this._physicalTop, 0);
+
+      if (deltaHeight) {
+        this._physicalTop = this._physicalTop - deltaHeight;
+
+        // juking scroll position during interial scrolling on iOS is no bueno
+        if (!IOS_TOUCH_SCROLLING) {
+          this._resetScrollPosition(this._scroller.scrollTop - deltaHeight);
+        }
+      }
+    },
+
+    /**
+     * Sets the position of the scroll.
+     */
+    _resetScrollPosition: function(pos) {
+      if (this._scroller) {
+        this._scroller.scrollTop = pos;
+        this._scrollPosition = this._scroller.scrollTop;
+      }
+    },
+
+    /**
+     * Sets the scroll height, that's the height of the content,
+     * 
+     * @param {boolean=} forceUpdate If true, updates the height no matter what.
+     */
+    _updateScrollerSize: function(forceUpdate) {
+      this._estScrollHeight = (this._physicalBottom +
+          Math.max(this._virtualCount - this._physicalCount - this._virtualStartVal, 0) * this._physicalAverage);
+
+      forceUpdate = forceUpdate || this._scrollHeight === 0;
+      forceUpdate = forceUpdate || this._scrollPosition >= this._estScrollHeight - this._physicalSize;
+
+      // amortize height adjustment, so it won't trigger repaints very often
+      if (forceUpdate || Math.abs(this._estScrollHeight - this._scrollHeight) >= this._optPhysicalSize) {
+        this.$.items.style.height = this._estScrollHeight + 'px';
+        this._scrollHeight = this._estScrollHeight;
+      }
+    },
+
+    /**
+     * Scroll to a specific item in the virtual list regardless
+     * of the physical items in the DOM tree.
+     *
+     * @method scrollToIndex
+     * @param {number} idx The index of the item
+     */
+    scrollToIndex: function(idx) {
+      if (typeof idx !== 'number') {
+        return;
+      }
+
+      var firstVisible = this.firstVisibleIndex;
+
+      idx = Math.min(Math.max(idx, 0), this._virtualCount-1);
+
+      // start at the previous virtual item
+      // so we have a item above the first visible item
+      this._virtualStart = idx - 1;
+
+      // assign new models
+      this._assignModels();
+
+      // measure the new sizes
+      this._updateMetrics();
+
+      // estimate new physical offset
+      this._physicalTop = this._virtualStart * this._physicalAverage;
+
+      var currentTopItem = this._physicalStart;
+      var currentVirtualItem = this._virtualStart;
+      var targetOffsetTop = 0;
+      var hiddenContentSize = this._hiddenContentSize;
+
+      // scroll to the item as much as we can
+      while (currentVirtualItem !== idx && targetOffsetTop < hiddenContentSize) {
+        targetOffsetTop = targetOffsetTop + this._physicalSizes[currentTopItem];
+        currentTopItem = (currentTopItem + 1) % this._physicalCount;
+        currentVirtualItem++;
+      }
+
+      // update the scroller size
+      this._updateScrollerSize(true);
+
+      // update the position of the items
+      this._positionItems();
+
+      // set the new scroll position
+      this._resetScrollPosition(this._physicalTop + targetOffsetTop + 1);
+
+      // increase the pool of physical items if needed
+      if (this._increasePoolIfNeeded()) {
+        // set models to the new items
+        this.async(this._update);
+      }
+
+      // clear cached visible index
+      this._firstVisibleIndexVal = null;
+    },
+
+    /**
+     * Reset the physical average and the average count.
+     */
+    _resetAverage: function() {
+      this._physicalAverage = 0;
+      this._physicalAverageCount = 0;
+    },
+
+    /**
+     * A handler for the `iron-resize` event triggered by `IronResizableBehavior`
+     * when the element is resized.
+     */
+    _resizeHandler: function() {
+      this.debounce('resize', function() {
+        this._render();
+        if (this._itemsRendered && this._physicalItems && this._isVisible) {
+          this._resetAverage();
+          this.updateViewportBoundaries();
+          this.scrollToIndex(this.firstVisibleIndex);
+        }
+      });
+    },
+
+    _getModelFromItem: function(item) {
+      var key = this._collection.getKey(item);
+      var pidx = this._physicalIndexForKey[key];
+
+      if (pidx !== undefined) {
+        return this._physicalItems[pidx]._templateInstance;
+      }
+      return null;
+    },
+
+    /**
+     * Gets a valid item instance from its index or the object value.
+     *
+     * @param {(Object|number)} item The item object or its index
+     */
+    _getNormalizedItem: function(item) {
+      if (typeof item === 'number') {
+        item = this.items[item];
+        if (!item) {
+          throw new RangeError('<item> not found');
+        }
+      } else if (this._collection.getKey(item) === undefined) {
+        throw new TypeError('<item> should be a valid item');
+      }
+      return item;
+    },
+
+    /**
+     * Select the list item at the given index.
+     *
+     * @method selectItem
+     * @param {(Object|number)} item The item object or its index
+     */
+    selectItem: function(item) {
+      item = this._getNormalizedItem(item);
+      var model = this._getModelFromItem(item);
+
+      if (!this.multiSelection && this.selectedItem) {
+        this.deselectItem(this.selectedItem);
+      }
+      if (model) {
+        model[this.selectedAs] = true;
+      }
+      this.$.selector.select(item);
+    },
+
+    /**
+     * Deselects the given item list if it is already selected.
+     *
+
+     * @method deselect
+     * @param {(Object|number)} item The item object or its index
+     */
+    deselectItem: function(item) {
+      item = this._getNormalizedItem(item);
+      var model = this._getModelFromItem(item);
+
+      if (model) {
+        model[this.selectedAs] = false;
+      }
+      this.$.selector.deselect(item);
+    },
+
+    /**
+     * Select or deselect a given item depending on whether the item
+     * has already been selected.
+     *
+     * @method toggleSelectionForItem
+     * @param {(Object|number)} item The item object or its index
+     */
+    toggleSelectionForItem: function(item) {
+      item = this._getNormalizedItem(item);
+      if (/** @type {!ArraySelectorElement} */ (this.$.selector).isSelected(item)) {
+        this.deselectItem(item);
+      } else {
+        this.selectItem(item);
+      }
+    },
+
+    /**
+     * Clears the current selection state of the list.
+     *
+     * @method clearSelection
+     */
+    clearSelection: function() {
+      function unselect(item) {
+        var model = this._getModelFromItem(item);
+        if (model) {
+          model[this.selectedAs] = false;
+        }
+      }
+
+      if (Array.isArray(this.selectedItems)) {
+        this.selectedItems.forEach(unselect, this);
+      } else if (this.selectedItem) {
+        unselect.call(this, this.selectedItem);
+      }
+
+      /** @type {!ArraySelectorElement} */ (this.$.selector).clearSelection();
+    },
+
+    /**
+     * Add an event listener to `tap` if `selectionEnabled` is true,
+     * it will remove the listener otherwise.
+     */
+    _selectionEnabledChanged: function(selectionEnabled) {
+      if (selectionEnabled) {
+        this.listen(this, 'tap', '_selectionHandler');
+        this.listen(this, 'keypress', '_selectionHandler');
+      } else {
+        this.unlisten(this, 'tap', '_selectionHandler');
+        this.unlisten(this, 'keypress', '_selectionHandler');
+      }
+    },
+
+    /**
+     * Select an item from an event object.
+     */
+    _selectionHandler: function(e) {
+      if (e.type !== 'keypress' || e.keyCode === 13) {
+        var model = this.modelForElement(e.target);
+        if (model) {
+          this.toggleSelectionForItem(model[this.as]);
+        }
+      }
+    },
+
+    _multiSelectionChanged: function(multiSelection) {
+      this.clearSelection();
+      this.$.selector.multi = multiSelection;
+    },
+
+    /**
+     * Updates the size of an item.
+     *
+     * @method updateSizeForItem
+     * @param {(Object|number)} item The item object or its index
+     */
+    updateSizeForItem: function(item) {
+      item = this._getNormalizedItem(item);
+      var key = this._collection.getKey(item);
+      var pidx = this._physicalIndexForKey[key];
+
+      if (pidx !== undefined) {
+        this._updateMetrics([pidx]);
+        this._positionItems();
+      }
+    }
+  });
+
+})();
 (function() {
 
     'use strict';
 
     var SHADOW_WHEN_SCROLLING = 1;
     var SHADOW_ALWAYS = 2;
 
 
     var MODE_CONFIGS = {
 
@@ skipping 227 matching lines @@
       },
 
       _getScrollerForMode: function(mode) {
         return MODE_CONFIGS.outerScroll[mode] ?
             this : this.$.mainContainer;
       }
 
     });
 
   })();
+(function() {
+
+    // monostate data
+    var metaDatas = {};
+    var metaArrays = {};
+
+    Polymer.IronMeta = Polymer({
+
+      is: 'iron-meta',
+
+      properties: {
+
+        /**
+         * The type of meta-data.  All meta-data of the same type is stored
+         * together.
+         */
+        type: {
+          type: String,
+          value: 'default',
+          observer: '_typeChanged'
+        },
+
+        /**
+         * The key used to store `value` under the `type` namespace.
+         */
+        key: {
+          type: String,
+          observer: '_keyChanged'
+        },
+
+        /**
+         * The meta-data to store or retrieve.
+         */
+        value: {
+          type: Object,
+          notify: true,
+          observer: '_valueChanged'
+        },
+
+        /**
+         * If true, `value` is set to the iron-meta instance itself.
+         */
+         self: {
+          type: Boolean,
+          observer: '_selfChanged'
+        },
+
+        /**
+         * Array of all meta-data values for the given type.
+         */
+        list: {
+          type: Array,
+          notify: true
+        }
+
+      },
+
+      /**
+       * Only runs if someone invokes the factory/constructor directly
+       * e.g. `new Polymer.IronMeta()`
+       */
+      factoryImpl: function(config) {
+        if (config) {
+          for (var n in config) {
+            switch(n) {
+              case 'type':
+              case 'key':
+              case 'value':
+                this[n] = config[n];
+                break;
+            }
+          }
+        }
+      },
+
+      created: function() {
+        // TODO(sjmiles): good for debugging?
+        this._metaDatas = metaDatas;
+        this._metaArrays = metaArrays;
+      },
+
+      _keyChanged: function(key, old) {
+        this._resetRegistration(old);
+      },
+
+      _valueChanged: function(value) {
+        this._resetRegistration(this.key);
+      },
+
+      _selfChanged: function(self) {
+        if (self) {
+          this.value = this;
+        }
+      },
+
+      _typeChanged: function(type) {
+        this._unregisterKey(this.key);
+        if (!metaDatas[type]) {
+          metaDatas[type] = {};
+        }
+        this._metaData = metaDatas[type];
+        if (!metaArrays[type]) {
+          metaArrays[type] = [];
+        }
+        this.list = metaArrays[type];
+        this._registerKeyValue(this.key, this.value);
+      },
+
+      /**
+       * Retrieves meta data value by key.
+       *
+       * @method byKey
+       * @param {string} key The key of the meta-data to be returned.
+       * @return {*}
+       */
+      byKey: function(key) {
+        return this._metaData && this._metaData[key];
+      },
+
+      _resetRegistration: function(oldKey) {
+        this._unregisterKey(oldKey);
+        this._registerKeyValue(this.key, this.value);
+      },
+
+      _unregisterKey: function(key) {
+        this._unregister(key, this._metaData, this.list);
+      },
+
+      _registerKeyValue: function(key, value) {
+        this._register(key, value, this._metaData, this.list);
+      },
+
+      _register: function(key, value, data, list) {
+        if (key && data && value !== undefined) {
+          data[key] = value;
+          list.push(value);
+        }
+      },
+
+      _unregister: function(key, data, list) {
+        if (key && data) {
+          if (key in data) {
+            var value = data[key];
+            delete data[key];
+            this.arrayDelete(list, value);
+          }
+        }
+      }
+
+    });
+
+    /**
+    `iron-meta-query` can be used to access infomation stored in `iron-meta`.
+
+    Examples:
+
+    If I create an instance like this:
+
+        <iron-meta key="info" value="foo/bar"></iron-meta>
+
+    Note that value="foo/bar" is the metadata I've defined. I could define more
+    attributes or use child nodes to define additional metadata.
+
+    Now I can access that element (and it's metadata) from any `iron-meta-query` instance:
+
+         var value = new Polymer.IronMetaQuery({key: 'info'}).value;
+
+    @group Polymer Iron Elements
+    @element iron-meta-query
+    */
+    Polymer.IronMetaQuery = Polymer({
+
+      is: 'iron-meta-query',
+
+      properties: {
+
+        /**
+         * The type of meta-data.  All meta-data of the same type is stored
+         * together.
+         */
+        type: {
+          type: String,
+          value: 'default',
+          observer: '_typeChanged'
+        },
+
+        /**
+         * Specifies a key to use for retrieving `value` from the `type`
+         * namespace.
+         */
+        key: {
+          type: String,
+          observer: '_keyChanged'
+        },
+
+        /**
+         * The meta-data to store or retrieve.
+         */
+        value: {
+          type: Object,
+          notify: true,
+          readOnly: true
+        },
+
+        /**
+         * Array of all meta-data values for the given type.
+         */
+        list: {
+          type: Array,
+          notify: true
+        }
+
+      },
+
+      /**
+       * Actually a factory method, not a true constructor. Only runs if
+       * someone invokes it directly (via `new Polymer.IronMeta()`);
+       */
+      factoryImpl: function(config) {
+        if (config) {
+          for (var n in config) {
+            switch(n) {
+              case 'type':
+              case 'key':
+                this[n] = config[n];
+                break;
+            }
+          }
+        }
+      },
+
+      created: function() {
+        // TODO(sjmiles): good for debugging?
+        this._metaDatas = metaDatas;
+        this._metaArrays = metaArrays;
+      },
+
+      _keyChanged: function(key) {
+        this._setValue(this._metaData && this._metaData[key]);
+      },
+
+      _typeChanged: function(type) {
+        this._metaData = metaDatas[type];
+        this.list = metaArrays[type];
+        if (this.key) {
+          this._keyChanged(this.key);
+        }
+      },
+
+      /**
+       * Retrieves meta data value by key.
+       * @param {string} key The key of the meta-data to be returned.
+       * @return {*}
+       */
+      byKey: function(key) {
+        return this._metaData && this._metaData[key];
+      }
+
+    });
+
+  })();
+Polymer({
+
+      is: 'iron-icon',
+
+      properties: {
+
+        /**
+         * The name of the icon to use. The name should be of the form:
+         * `iconset_name:icon_name`.
+         */
+        icon: {
+          type: String,
+          observer: '_iconChanged'
+        },
+
+        /**
+         * The name of the theme to used, if one is specified by the
+         * iconset.
+         */
+        theme: {
+          type: String,
+          observer: '_updateIcon'
+        },
+
+        /**
+         * If using iron-icon without an iconset, you can set the src to be
+         * the URL of an individual icon image file. Note that this will take
+         * precedence over a given icon attribute.
+         */
+        src: {
+          type: String,
+          observer: '_srcChanged'
+        },
+
+        /**
+         * @type {!Polymer.IronMeta}
+         */
+        _meta: {
+          value: Polymer.Base.create('iron-meta', {type: 'iconset'})
+        }
+
+      },
+
+      _DEFAULT_ICONSET: 'icons',
+
+      _iconChanged: function(icon) {
+        var parts = (icon || '').split(':');
+        this._iconName = parts.pop();
+        this._iconsetName = parts.pop() || this._DEFAULT_ICONSET;
+        this._updateIcon();
+      },
+
+      _srcChanged: function(src) {
+        this._updateIcon();
+      },
+
+      _usesIconset: function() {
+        return this.icon || !this.src;
+      },
+
+      /** @suppress {visibility} */
+      _updateIcon: function() {
+        if (this._usesIconset()) {
+          if (this._iconsetName) {
+            this._iconset = /** @type {?Polymer.Iconset} */ (
+              this._meta.byKey(this._iconsetName));
+            if (this._iconset) {
+              this._iconset.applyIcon(this, this._iconName, this.theme);
+              this.unlisten(window, 'iron-iconset-added', '_updateIcon');
+            } else {
+              this.listen(window, 'iron-iconset-added', '_updateIcon');
+            }
+          }
+        } else {
+          if (!this._img) {
+            this._img = document.createElement('img');
+            this._img.style.width = '100%';
+            this._img.style.height = '100%';
+            this._img.draggable = false;
+          }
+          this._img.src = this.src;
+          Polymer.dom(this.root).appendChild(this._img);
+        }
+      }
+
+    });
+/**
+   * The `iron-iconset-svg` element allows users to define their own icon sets
+   * that contain svg icons. The svg icon elements should be children of the
+   * `iron-iconset-svg` element. Multiple icons should be given distinct id's.
+   *
+   * Using svg elements to create icons has a few advantages over traditional
+   * bitmap graphics like jpg or png. Icons that use svg are vector based so they
+   * are resolution independent and should look good on any device. They are
+   * stylable via css. Icons can be themed, colorized, and even animated.
+   *
+   * Example:
+   *
+   *     <iron-iconset-svg name="my-svg-icons" size="24">
+   *       <svg>
+   *         <defs>
+   *           <g id="shape">
+   *             <rect x="50" y="50" width="50" height="50" />
+   *             <circle cx="50" cy="50" r="50" />
+   *           </g>
+   *         </defs>
+   *       </svg>
+   *     </iron-iconset-svg>
+   *
+   * This will automatically register the icon set "my-svg-icons" to the iconset
+   * database.  To use these icons from within another element, make a
+   * `iron-iconset` element and call the `byId` method
+   * to retrieve a given iconset. To apply a particular icon inside an
+   * element use the `applyIcon` method. For example:
+   *
+   *     iconset.applyIcon(iconNode, 'car');
+   *
+   * @element iron-iconset-svg
+   * @demo demo/index.html
+   */
+  Polymer({
+
+    is: 'iron-iconset-svg',
+
+    properties: {
+
+      /**
+       * The name of the iconset.
+       *
+       * @attribute name
+       * @type string
+       */
+      name: {
+        type: String,
+        observer: '_nameChanged'
+      },
+
+      /**
+       * The size of an individual icon. Note that icons must be square.
+       *
+       * @attribute iconSize
+       * @type number
+       * @default 24
+       */
+      size: {
+        type: Number,
+        value: 24
+      }
+
+    },
+
+    /**
+     * Construct an array of all icon names in this iconset.
+     *
+     * @return {!Array} Array of icon names.
+     */
+    getIconNames: function() {
+      this._icons = this._createIconMap();
+      return Object.keys(this._icons).map(function(n) {
+        return this.name + ':' + n;
+      }, this);
+    },
+
+    /**
+     * Applies an icon to the given element.
+     *
+     * An svg icon is prepended to the element's shadowRoot if it exists,
+     * otherwise to the element itself.
+     *
+     * @method applyIcon
+     * @param {Element} element Element to which the icon is applied.
+     * @param {string} iconName Name of the icon to apply.
+     * @return {Element} The svg element which renders the icon.
+     */
+    applyIcon: function(element, iconName) {
+      // insert svg element into shadow root, if it exists
+      element = element.root || element;
+      // Remove old svg element
+      this.removeIcon(element);
+      // install new svg element
+      var svg = this._cloneIcon(iconName);
+      if (svg) {
+        var pde = Polymer.dom(element);
+        pde.insertBefore(svg, pde.childNodes[0]);
+        return element._svgIcon = svg;
+      }
+      return null;
+    },
+
+    /**
+     * Remove an icon from the given element by undoing the changes effected
+     * by `applyIcon`.
+     *
+     * @param {Element} element The element from which the icon is removed.
+     */
+    removeIcon: function(element) {
+      // Remove old svg element
+      if (element._svgIcon) {
+        Polymer.dom(element).removeChild(element._svgIcon);
+        element._svgIcon = null;
+      }
+    },
+
+    /**
+     *
+     * When name is changed, register iconset metadata
+     *
+     */
+    _nameChanged: function() {
+      new Polymer.IronMeta({type: 'iconset', key: this.name, value: this});
+      this.async(function() {
+        this.fire('iron-iconset-added', this, {node: window});
+      });
+    },
+
+    /**
+     * Create a map of child SVG elements by id.
+     *
+     * @return {!Object} Map of id's to SVG elements.
+     */
+    _createIconMap: function() {
+      // Objects chained to Object.prototype (`{}`) have members. Specifically,
+      // on FF there is a `watch` method that confuses the icon map, so we
+      // need to use a null-based object here.
+      var icons = Object.create(null);
+      Polymer.dom(this).querySelectorAll('[id]')
+        .forEach(function(icon) {
+          icons[icon.id] = icon;
+        });
+      return icons;
+    },
+
+    /**
+     * Produce installable clone of the SVG element matching `id` in this
+     * iconset, or `undefined` if there is no matching element.
+     *
+     * @return {Element} Returns an installable clone of the SVG element
+     * matching `id`.
+     */
+    _cloneIcon: function(id) {
+      // create the icon map on-demand, since the iconset itself has no discrete
+      // signal to know when it's children are fully parsed
+      this._icons = this._icons || this._createIconMap();
+      return this._prepareSvgClone(this._icons[id], this.size);
+    },
+
+    /**
+     * @param {Element} sourceSvg
+     * @param {number} size
+     * @return {Element}
+     */
+    _prepareSvgClone: function(sourceSvg, size) {
+      if (sourceSvg) {
+        var content = sourceSvg.cloneNode(true),
+            svg = document.createElementNS('http://www.w3.org/2000/svg', 'svg'),
+            viewBox = content.getAttribute('viewBox') || '0 0 ' + size + ' ' + size;
+        svg.setAttribute('viewBox', viewBox);
+        svg.setAttribute('preserveAspectRatio', 'xMidYMid meet');
+        // TODO(dfreedm): `pointer-events: none` works around https://crbug.com/370136
+        // TODO(sjmiles): inline style may not be ideal, but avoids requiring a shadow-root
+        svg.style.cssText = 'pointer-events: none; display: block; width: 100%; height: 100%;';
+        svg.appendChild(content).removeAttribute('id');
+        return svg;
+      }
+      return null;
+    }
+
+  });
 Polymer({
     is: 'paper-material',
 
     properties: {
 
       /**
        * The z-depth of this element, from 0-5. Setting to 0 will remove the
        * shadow, and each increasing number greater than 0 will be "deeper"
        * than the last.
        *
@@ skipping 800 matching lines @@
         /**
          * If true, the ripple will remain in the "down" state until `holdDown`
          * is set to false again.
          */
         holdDown: {
           type: Boolean,
           value: false,
           observer: '_holdDownChanged'
         },
 
+        /**
+         * If true, the ripple will not generate a ripple effect 
+         * via pointer interaction.
+         * Calling ripple's imperative api like `simulatedRipple` will 
+         * still generate the ripple effect.
+         */
+        noink: {
+          type: Boolean,
+          value: false
+        },
+
         _animating: {
           type: Boolean
         },
 
         _boundAnimate: {
           type: Function,
           value: function() {
             return this.animate.bind(this);
           }
         }
       },
 
+      observers: [
+        '_noinkChanged(noink, isAttached)'
+      ],
+
       get target () {
         var ownerRoot = Polymer.dom(this).getOwnerRoot();
         var target;
 
         if (this.parentNode.nodeType == 11) { // DOCUMENT_FRAGMENT_NODE
           target = ownerRoot.host;
         } else {
           target = this.parentNode;
         }
 
         return target;
       },
 
       keyBindings: {
         'enter:keydown': '_onEnterKeydown',
         'space:keydown': '_onSpaceKeydown',
         'space:keyup': '_onSpaceKeyup'
       },
 
       attached: function() {
-        this.listen(this.target, 'up', 'upAction');
-        this.listen(this.target, 'down', 'downAction');
-
-        if (!this.target.hasAttribute('noink')) {
-          this.keyEventTarget = this.target;
-        }
+        this.listen(this.target, 'up', 'uiUpAction');
+        this.listen(this.target, 'down', 'uiDownAction');
+      },
+
+      detached: function() {
+        this.unlisten(this.target, 'up', 'uiUpAction');
+        this.unlisten(this.target, 'down', 'uiDownAction');
       },
 
       get shouldKeepAnimating () {
         for (var index = 0; index < this.ripples.length; ++index) {
           if (!this.ripples[index].isAnimationComplete) {
             return true;
           }
         }
 
         return false;
       },
 
       simulatedRipple: function() {
         this.downAction(null);
 
         // Please see polymer/polymer#1305
         this.async(function() {
           this.upAction();
         }, 1);
       },
 
-      /** @param {Event=} event */
+      /** 
+       * Provokes a ripple down effect via a UI event, 
+       * respecting the `noink` property.
+       * @param {Event=} event 
+       */
+      uiDownAction: function(event) {
+        if (!this.noink) {
+          this.downAction(event);
+        }
+      },
+
+      /** 
+       * Provokes a ripple down effect via a UI event, 
+       * *not* respecting the `noink` property.
+       * @param {Event=} event 
+       */
       downAction: function(event) {
         if (this.holdDown && this.ripples.length > 0) {
           return;
         }
 
         var ripple = this.addRipple();
 
         ripple.downAction(event);
 
         if (!this._animating) {
           this.animate();
         }
       },
 
-      /** @param {Event=} event */
+      /** 
+       * Provokes a ripple up effect via a UI event, 
+       * respecting the `noink` property.
+       * @param {Event=} event 
+       */
+      uiUpAction: function(event) {
+        if (!this.noink) {
+          this.upAction(event);
+        }
+      },
+
+      /** 
+       * Provokes a ripple up effect via a UI event, 
+       * *not* respecting the `noink` property.
+       * @param {Event=} event 
+       */
       upAction: function(event) {
         if (this.holdDown) {
           return;
         }
 
         this.ripples.forEach(function(ripple) {
           ripple.upAction(event);
         });
 
         this.animate();
@@ skipping 52 matching lines @@
         }
 
         if (!this.shouldKeepAnimating && this.ripples.length === 0) {
           this.onAnimationComplete();
         } else {
           window.requestAnimationFrame(this._boundAnimate);
         }
       },
 
       _onEnterKeydown: function() {
-        this.downAction();
-        this.async(this.upAction, 1);
+        this.uiDownAction();
+        this.async(this.uiUpAction, 1);
       },
 
       _onSpaceKeydown: function() {
-        this.downAction();
+        this.uiDownAction();
       },
 
       _onSpaceKeyup: function() {
-        this.upAction();
-      },
-
-      _holdDownChanged: function(holdDown) {
-        if (holdDown) {
+        this.uiUpAction();
+      },
+
+      // note: holdDown does not respect noink since it can be a focus based
+      // effect.
+      _holdDownChanged: function(newVal, oldVal) {
+        if (oldVal === undefined) {
+          return;
+        }
+        if (newVal) {
           this.downAction();
         } else {
           this.upAction();
         }
+      },
+
+      _noinkChanged: function(noink, attached) {
+        if (attached) {
+          this.keyEventTarget = noink ? this : this.target;
+        }
       }
     });
   })();
 /**
    * @demo demo/index.html
    * @polymerBehavior
    */
   Polymer.IronControlState = {
 
     properties: {
@@ skipping 185 matching lines @@
 
     // to emulate native checkbox, (de-)activations from a user interaction fire
     // 'change' events
     _userActivate: function(active) {
       if (this.active !== active) {
         this.active = active;
         this.fire('change');
       }
     },
 
-    _eventSourceIsPrimaryInput: function(event) {
-      event = event.detail.sourceEvent || event;
-
-      // Always true for non-mouse events....
-      if (!this._mouseEventRe.test(event.type)) {
-        return true;
-      }
-
-      // http://developer.mozilla.org/en-US/docs/Web/API/MouseEvent/buttons
-      if ('buttons' in event) {
-        return event.buttons === 1;
-      }
-
-      // http://developer.mozilla.org/en-US/docs/Web/API/MouseEvent/which
-      if (typeof event.which === 'number') {
-        return event.which < 2;
-      }
-
-      // http://developer.mozilla.org/en-US/docs/Web/API/MouseEvent/button
-      return event.button < 1;
-    },
-
     _downHandler: function(event) {
-      if (!this._eventSourceIsPrimaryInput(event)) {
-        return;
-      }
-
       this._setPointerDown(true);
       this._setPressed(true);
       this._setReceivedFocusFromKeyboard(false);
     },
 
     _upHandler: function() {
       this._setPointerDown(false);
       this._setPressed(false);
     },
 
@@ skipping 57 matching lines @@
       }
     }
 
   };
 
   /** @polymerBehavior */
   Polymer.IronButtonState = [
     Polymer.IronA11yKeysBehavior,
     Polymer.IronButtonStateImpl
   ];
-/** @polymerBehavior */
+/** 
+   * `Polymer.PaperRippleBehavior` dynamically implements a ripple 
+   * when the element has focus via pointer or keyboard.
+   *
+   * NOTE: This behavior is intended to be used in conjunction with and after
+   * `Polymer.IronButtonState` and `Polymer.IronControlState`.
+   *
+   * @polymerBehavior Polymer.PaperRippleBehavior 
+   */
+  Polymer.PaperRippleBehavior = {
+
+    properties: {
+      /**
+       * If true, the element will not produce a ripple effect when interacted
+       * with via the pointer.
+       */
+      noink: {
+        type: Boolean,
+        observer: '_noinkChanged'
+      }
+    },
+
+    /**
+     * Ensures a `<paper-ripple>` element is available when the element is 
+     * focused.
+     */
+    _buttonStateChanged: function() {
+      if (this.focused) {
+        this.ensureRipple();
+      }
+    },
+
+    /** 
+     * In addition to the functionality provided in `IronButtonState`, ensures
+     * a ripple effect is created when the element is in a `pressed` state.
+     */
+    _downHandler: function(event) {
+      Polymer.IronButtonStateImpl._downHandler.call(this, event);
+      if (this.pressed) {
+        this.ensureRipple(event);
+      }
+    },
+
+    /**
+     * Ensures this element contains a ripple effect. For startup efficiency 
+     * the ripple effect is dynamically on demand when needed.
+     * @param {!Event=} opt_triggeringEvent (optional) event that triggered the
+     * ripple.
+     */
+    ensureRipple: function(opt_triggeringEvent) {
+      if (!this.hasRipple()) {
+        this._ripple = this._createRipple();
+        this._ripple.noink = this.noink;
+        var rippleContainer = this._rippleContainer || this.root;
+        if (rippleContainer) {
+          Polymer.dom(rippleContainer).appendChild(this._ripple);
+        }
+        var domContainer = rippleContainer === this.shadyRoot ? this : 
+          rippleContainer;
+        if (opt_triggeringEvent &&
+            domContainer.contains(opt_triggeringEvent.target)) {
+          this._ripple.uiDownAction(opt_triggeringEvent);
+        }
+      }
+    },
+
+    /**
+     * Returns the `<paper-ripple>` element used by this element to create
+     * ripple effects. The element's ripple is created on demand, when
+     * necessary, and calling this method will force the 
+     * ripple to be created.
+     */
+    getRipple: function() {
+      this.ensureRipple();
+      return this._ripple;
+    },
+
+    /**
+     * Returns true if this element currently contains a ripple effect.
+     * @return {boolean}
+     */
+    hasRipple: function() {
+      return Boolean(this._ripple);
+    },
+
+    /**
+     * Create the element's ripple effect via creating a `<paper-ripple>`.
+     * Override this method to customize the ripple element.
+     * @return {element} Returns a `<paper-ripple>` element.
+     */
+    _createRipple: function() {
+      return document.createElement('paper-ripple');
+    },
+
+    _noinkChanged: function(noink) {
+      if (this.hasRipple()) {
+        this._ripple.noink = noink;
+      }
+    }
+
+  };
+/** @polymerBehavior Polymer.PaperButtonBehavior */
   Polymer.PaperButtonBehaviorImpl = {
 
     properties: {
 
-      _elevation: {
-        type: Number
+      /**
+       * The z-depth of this element, from 0-5. Setting to 0 will remove the
+       * shadow, and each increasing number greater than 0 will be "deeper"
+       * than the last.
+       *
+       * @attribute elevation
+       * @type number
+       * @default 1
+       */
+      elevation: {
+        type: Number,
+        reflectToAttribute: true,
+        readOnly: true
       }
 
     },
 
     observers: [
-      '_calculateElevation(focused, disabled, active, pressed, receivedFocusFromKeyboard)'
+      '_calculateElevation(focused, disabled, active, pressed, receivedFocusFromKeyboard)',
+      '_computeKeyboardClass(receivedFocusFromKeyboard)'
     ],
 
     hostAttributes: {
       role: 'button',
-      tabindex: '0'
+      tabindex: '0',
+      animated: true
     },
 
     _calculateElevation: function() {
       var e = 1;
       if (this.disabled) {
         e = 0;
       } else if (this.active || this.pressed) {
         e = 4;
       } else if (this.receivedFocusFromKeyboard) {
         e = 3;
       }
-      this._elevation = e;
+      this._setElevation(e);
+    },
+
+    _computeKeyboardClass: function(receivedFocusFromKeyboard) {
+      this.classList.toggle('keyboard-focus', receivedFocusFromKeyboard);
+    },
+
+    /**
+     * In addition to `IronButtonState` behavior, when space key goes down, 
+     * create a ripple down effect.
+     */
+    _spaceKeyDownHandler: function(event) {
+      Polymer.IronButtonStateImpl._spaceKeyDownHandler.call(this, event);
+      if (this.hasRipple()) {
+        this._ripple.uiDownAction();
+      }
+    },
+
+    /**
+     * In addition to `IronButtonState` behavior, when space key goes up, 
+     * create a ripple up effect.
+     */
+    _spaceKeyUpHandler: function(event) {
+      Polymer.IronButtonStateImpl._spaceKeyUpHandler.call(this, event);
+      if (this.hasRipple()) {
+        this._ripple.uiUpAction();
+      }
     }
+
   };
 
   /** @polymerBehavior */
   Polymer.PaperButtonBehavior = [
     Polymer.IronButtonState,
     Polymer.IronControlState,
+    Polymer.PaperRippleBehavior,
     Polymer.PaperButtonBehaviorImpl
   ];
 Polymer({
     is: 'paper-button',
 
     behaviors: [
       Polymer.PaperButtonBehavior
     ],
 
     properties: {
       /**
        * If true, the button should be styled with a shadow.
        */
       raised: {
         type: Boolean,
         reflectToAttribute: true,
         value: false,
         observer: '_calculateElevation'
       }
     },
 
     _calculateElevation: function() {
       if (!this.raised) {
-        this._elevation = 0;
+        this.elevation = 0;
       } else {
         Polymer.PaperButtonBehaviorImpl._calculateElevation.apply(this);
       }
-    },
-
-    _computeContentClass: function(receivedFocusFromKeyboard) {
-      var className = 'content ';
-      if (receivedFocusFromKeyboard) {
-        className += ' keyboard-focus';
-      }
-      return className;
     }
   });
 /** 
  * `iron-range-behavior` provides the behavior for something with a minimum to maximum range.
  *
  * @demo demo/index.html
  * @polymerBehavior 
  */
  Polymer.IronRangeBehavior = {
 
@@ skipping 183 matching lines @@
 
   });
 // Copyright 2015 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 cr.define('downloads', function() {
   var Item = Polymer({
     is: 'downloads-item',
 
-    /**
-     * @param {!downloads.ThrottledIconLoader} iconLoader
-     */
-    factoryImpl: function(iconLoader) {
-      /** @private {!downloads.ThrottledIconLoader} */
-      this.iconLoader_ = iconLoader;
-    },
-
     properties: {
       data: {
         type: Object,
       },
 
       hideDate: {
         type: Boolean,
         value: true,
       },
 
-      readyPromise: {
-        type: Object,
-        value: function() {
-          return new Promise(function(resolve, reject) {
-            this.resolveReadyPromise_ = resolve;
-          }.bind(this));
-        },
-      },
-
       completelyOnDisk_: {
         computed: 'computeCompletelyOnDisk_(' +
             'data.state, data.file_externally_removed)',
         type: Boolean,
         value: true,
       },
 
       controlledBy_: {
         computed: 'computeControlledBy_(data.by_ext_id, data.by_ext_name)',
         type: String,
@@ skipping 52 matching lines @@
         computed: 'computeIsMalware_(isDangerous_, data.danger_type)',
         type: Boolean,
         value: false,
       },
     },
 
     observers: [
       // TODO(dbeam): this gets called way more when I observe data.by_ext_id
       // and data.by_ext_name directly. Why?
       'observeControlledBy_(controlledBy_)',
+      'observeIsDangerous_(isDangerous_, data.file_path)',
     ],
 
     ready: function() {
       this.content = this.$.content;
-      this.resolveReadyPromise_();
-    },
-
-    /** @param {!downloads.Data} data */
-    update: function(data) {
-      this.data = data;
-
-      if (!this.isDangerous_) {
-        var icon = 'chrome://fileicon/' + encodeURIComponent(data.file_path);
-        this.iconLoader_.loadScaledIcon(this.$['file-icon'], icon);
-      }
     },
 
     /** @private */
     computeClass_: function() {
       var classes = [];
 
       if (this.isActive_)
         classes.push('is-active');
 
       if (this.isDangerous_)
@@ skipping 15 matching lines @@
     computeControlledBy_: function() {
       if (!this.data.by_ext_id || !this.data.by_ext_name)
         return '';
 
       var url = 'chrome://extensions#' + this.data.by_ext_id;
       var name = this.data.by_ext_name;
       return loadTimeData.getStringF('controlledByUrl', url, name);
     },
 
     /** @private */
+    computeDangerIcon_: function() {
+      if (!this.isDangerous_)
+        return '';
+
+      switch (this.data.danger_type) {
+        case downloads.DangerType.DANGEROUS_CONTENT:
+        case downloads.DangerType.DANGEROUS_HOST:
+        case downloads.DangerType.DANGEROUS_URL:
+        case downloads.DangerType.POTENTIALLY_UNWANTED:
+        case downloads.DangerType.UNCOMMON_CONTENT:
+          return 'remove-circle';
+        default:
+          return 'warning';
+      }
+    },
+
+    /** @private */
     computeDate_: function() {
       if (this.hideDate)
         return '';
       return assert(this.data.since_string || this.data.date_string);
     },
 
     /** @private */
     computeDescription_: function() {
       var data = this.data;
 
@@ skipping 88 matching lines @@
     isIndeterminate_: function() {
       return this.data.percent == -1;
     },
 
     /** @private */
     observeControlledBy_: function() {
       this.$['controlled-by'].innerHTML = this.controlledBy_;
     },
 
     /** @private */
+    observeIsDangerous_: function() {
+      if (this.data && !this.isDangerous_) {
+        var filePath = encodeURIComponent(this.data.file_path);
+        this.$['file-icon'].src = 'chrome://fileicon/' + filePath;
+      }
+    },
+
+    /** @private */
     onCancelTap_: function() {
       downloads.ActionService.getInstance().cancel(this.data.id);
     },
 
     /** @private */
     onDiscardDangerousTap_: function() {
       downloads.ActionService.getInstance().discardDangerous(this.data.id);
     },
 
     /**
@@ skipping 40 matching lines @@
     },
 
     /** @private */
     onShowTap_: function() {
       downloads.ActionService.getInstance().show(this.data.id);
     },
   });
 
   return {Item: Item};
 });
-(function() {
-
-    // monostate data
-    var metaDatas = {};
-    var metaArrays = {};
-
-    Polymer.IronMeta = Polymer({
-
-      is: 'iron-meta',
-
-      properties: {
-
-        /**
-         * The type of meta-data.  All meta-data of the same type is stored
-         * together.
-         */
-        type: {
-          type: String,
-          value: 'default',
-          observer: '_typeChanged'
-        },
-
-        /**
-         * The key used to store `value` under the `type` namespace.
-         */
-        key: {
-          type: String,
-          observer: '_keyChanged'
-        },
-
-        /**
-         * The meta-data to store or retrieve.
-         */
-        value: {
-          type: Object,
-          notify: true,
-          observer: '_valueChanged'
-        },
-
-        /**
-         * If true, `value` is set to the iron-meta instance itself.
-         */
-         self: {
-          type: Boolean,
-          observer: '_selfChanged'
-        },
-
-        /**
-         * Array of all meta-data values for the given type.
-         */
-        list: {
-          type: Array,
-          notify: true
-        }
-
-      },
-
-      /**
-       * Only runs if someone invokes the factory/constructor directly
-       * e.g. `new Polymer.IronMeta()`
-       */
-      factoryImpl: function(config) {
-        if (config) {
-          for (var n in config) {
-            switch(n) {
-              case 'type':
-              case 'key':
-              case 'value':
-                this[n] = config[n];
-                break;
-            }
-          }
-        }
-      },
-
-      created: function() {
-        // TODO(sjmiles): good for debugging?
-        this._metaDatas = metaDatas;
-        this._metaArrays = metaArrays;
-      },
-
-      _keyChanged: function(key, old) {
-        this._resetRegistration(old);
-      },
-
-      _valueChanged: function(value) {
-        this._resetRegistration(this.key);
-      },
-
-      _selfChanged: function(self) {
-        if (self) {
-          this.value = this;
-        }
-      },
-
-      _typeChanged: function(type) {
-        this._unregisterKey(this.key);
-        if (!metaDatas[type]) {
-          metaDatas[type] = {};
-        }
-        this._metaData = metaDatas[type];
-        if (!metaArrays[type]) {
-          metaArrays[type] = [];
-        }
-        this.list = metaArrays[type];
-        this._registerKeyValue(this.key, this.value);
-      },
-
-      /**
-       * Retrieves meta data value by key.
-       *
-       * @method byKey
-       * @param {string} key The key of the meta-data to be returned.
-       * @return {*}
-       */
-      byKey: function(key) {
-        return this._metaData && this._metaData[key];
-      },
-
-      _resetRegistration: function(oldKey) {
-        this._unregisterKey(oldKey);
-        this._registerKeyValue(this.key, this.value);
-      },
-
-      _unregisterKey: function(key) {
-        this._unregister(key, this._metaData, this.list);
-      },
-
-      _registerKeyValue: function(key, value) {
-        this._register(key, value, this._metaData, this.list);
-      },
-
-      _register: function(key, value, data, list) {
-        if (key && data && value !== undefined) {
-          data[key] = value;
-          list.push(value);
-        }
-      },
-
-      _unregister: function(key, data, list) {
-        if (key && data) {
-          if (key in data) {
-            var value = data[key];
-            delete data[key];
-            this.arrayDelete(list, value);
-          }
-        }
-      }
-
-    });
-
-    /**
-    `iron-meta-query` can be used to access infomation stored in `iron-meta`.
-
-    Examples:
-
-    If I create an instance like this:
-
-        <iron-meta key="info" value="foo/bar"></iron-meta>
-
-    Note that value="foo/bar" is the metadata I've defined. I could define more
-    attributes or use child nodes to define additional metadata.
-
-    Now I can access that element (and it's metadata) from any `iron-meta-query` instance:
-
-         var value = new Polymer.IronMetaQuery({key: 'info'}).value;
-
-    @group Polymer Iron Elements
-    @element iron-meta-query
-    */
-    Polymer.IronMetaQuery = Polymer({
-
-      is: 'iron-meta-query',
-
-      properties: {
-
-        /**
-         * The type of meta-data.  All meta-data of the same type is stored
-         * together.
-         */
-        type: {
-          type: String,
-          value: 'default',
-          observer: '_typeChanged'
-        },
-
-        /**
-         * Specifies a key to use for retrieving `value` from the `type`
-         * namespace.
-         */
-        key: {
-          type: String,
-          observer: '_keyChanged'
-        },
-
-        /**
-         * The meta-data to store or retrieve.
-         */
-        value: {
-          type: Object,
-          notify: true,
-          readOnly: true
-        },
-
-        /**
-         * Array of all meta-data values for the given type.
-         */
-        list: {
-          type: Array,
-          notify: true
-        }
-
-      },
-
-      /**
-       * Actually a factory method, not a true constructor. Only runs if
-       * someone invokes it directly (via `new Polymer.IronMeta()`);
-       */
-      factoryImpl: function(config) {
-        if (config) {
-          for (var n in config) {
-            switch(n) {
-              case 'type':
-              case 'key':
-                this[n] = config[n];
-                break;
-            }
-          }
-        }
-      },
-
-      created: function() {
-        // TODO(sjmiles): good for debugging?
-        this._metaDatas = metaDatas;
-        this._metaArrays = metaArrays;
-      },
-
-      _keyChanged: function(key) {
-        this._setValue(this._metaData && this._metaData[key]);
-      },
-
-      _typeChanged: function(type) {
-        this._metaData = metaDatas[type];
-        this.list = metaArrays[type];
-        if (this.key) {
-          this._keyChanged(this.key);
-        }
-      },
-
-      /**
-       * Retrieves meta data value by key.
-       * @param {string} key The key of the meta-data to be returned.
-       * @return {*}
-       */
-      byKey: function(key) {
-        return this._metaData && this._metaData[key];
-      }
-
-    });
-
-  })();
-Polymer({
-
-      is: 'iron-icon',
-
-      properties: {
-
-        /**
-         * The name of the icon to use. The name should be of the form:
-         * `iconset_name:icon_name`.
-         */
-        icon: {
-          type: String,
-          observer: '_iconChanged'
-        },
-
-        /**
-         * The name of the theme to used, if one is specified by the
-         * iconset.
-         */
-        theme: {
-          type: String,
-          observer: '_updateIcon'
-        },
-
-        /**
-         * If using iron-icon without an iconset, you can set the src to be
-         * the URL of an individual icon image file. Note that this will take
-         * precedence over a given icon attribute.
-         */
-        src: {
-          type: String,
-          observer: '_srcChanged'
-        },
-
-        /**
-         * @type {!Polymer.IronMeta}
-         */
-        _meta: {
-          value: Polymer.Base.create('iron-meta', {type: 'iconset'})
-        }
-
-      },
-
-      _DEFAULT_ICONSET: 'icons',
-
-      _iconChanged: function(icon) {
-        var parts = (icon || '').split(':');
-        this._iconName = parts.pop();
-        this._iconsetName = parts.pop() || this._DEFAULT_ICONSET;
-        this._updateIcon();
-      },
-
-      _srcChanged: function(src) {
-        this._updateIcon();
-      },
-
-      _usesIconset: function() {
-        return this.icon || !this.src;
-      },
-
-      /** @suppress {visibility} */
-      _updateIcon: function() {
-        if (this._usesIconset()) {
-          if (this._iconsetName) {
-            this._iconset = /** @type {?Polymer.Iconset} */ (
-              this._meta.byKey(this._iconsetName));
-            if (this._iconset) {
-              this._iconset.applyIcon(this, this._iconName, this.theme);
-              this.unlisten(window, 'iron-iconset-added', '_updateIcon');
-            } else {
-              this.listen(window, 'iron-iconset-added', '_updateIcon');
-            }
-          }
-        } else {
-          if (!this._img) {
-            this._img = document.createElement('img');
-            this._img.style.width = '100%';
-            this._img.style.height = '100%';
-            this._img.draggable = false;
-          }
-          this._img.src = this.src;
-          Polymer.dom(this.root).appendChild(this._img);
-        }
-      }
-
-    });
-/**
-   * The `iron-iconset-svg` element allows users to define their own icon sets
-   * that contain svg icons. The svg icon elements should be children of the
-   * `iron-iconset-svg` element. Multiple icons should be given distinct id's.
-   *
-   * Using svg elements to create icons has a few advantages over traditional
-   * bitmap graphics like jpg or png. Icons that use svg are vector based so they
-   * are resolution independent and should look good on any device. They are
-   * stylable via css. Icons can be themed, colorized, and even animated.
-   *
-   * Example:
-   *
-   *     <iron-iconset-svg name="my-svg-icons" size="24">
-   *       <svg>
-   *         <defs>
-   *           <g id="shape">
-   *             <rect x="50" y="50" width="50" height="50" />
-   *             <circle cx="50" cy="50" r="50" />
-   *           </g>
-   *         </defs>
-   *       </svg>
-   *     </iron-iconset-svg>
-   *
-   * This will automatically register the icon set "my-svg-icons" to the iconset
-   * database.  To use these icons from within another element, make a
-   * `iron-iconset` element and call the `byId` method
-   * to retrieve a given iconset. To apply a particular icon inside an
-   * element use the `applyIcon` method. For example:
-   *
-   *     iconset.applyIcon(iconNode, 'car');
-   *
-   * @element iron-iconset-svg
-   * @demo demo/index.html
-   */
-  Polymer({
-
-    is: 'iron-iconset-svg',
-
-    properties: {
-
-      /**
-       * The name of the iconset.
-       *
-       * @attribute name
-       * @type string
-       */
-      name: {
-        type: String,
-        observer: '_nameChanged'
-      },
-
-      /**
-       * The size of an individual icon. Note that icons must be square.
-       *
-       * @attribute iconSize
-       * @type number
-       * @default 24
-       */
-      size: {
-        type: Number,
-        value: 24
-      }
-
-    },
-
-    /**
-     * Construct an array of all icon names in this iconset.
-     *
-     * @return {!Array} Array of icon names.
-     */
-    getIconNames: function() {
-      this._icons = this._createIconMap();
-      return Object.keys(this._icons).map(function(n) {
-        return this.name + ':' + n;
-      }, this);
-    },
-
-    /**
-     * Applies an icon to the given element.
-     *
-     * An svg icon is prepended to the element's shadowRoot if it exists,
-     * otherwise to the element itself.
-     *
-     * @method applyIcon
-     * @param {Element} element Element to which the icon is applied.
-     * @param {string} iconName Name of the icon to apply.
-     * @return {Element} The svg element which renders the icon.
-     */
-    applyIcon: function(element, iconName) {
-      // insert svg element into shadow root, if it exists
-      element = element.root || element;
-      // Remove old svg element
-      this.removeIcon(element);
-      // install new svg element
-      var svg = this._cloneIcon(iconName);
-      if (svg) {
-        var pde = Polymer.dom(element);
-        pde.insertBefore(svg, pde.childNodes[0]);
-        return element._svgIcon = svg;
-      }
-      return null;
-    },
-
-    /**
-     * Remove an icon from the given element by undoing the changes effected
-     * by `applyIcon`.
-     *
-     * @param {Element} element The element from which the icon is removed.
-     */
-    removeIcon: function(element) {
-      // Remove old svg element
-      if (element._svgIcon) {
-        Polymer.dom(element).removeChild(element._svgIcon);
-        element._svgIcon = null;
-      }
-    },
-
-    /**
-     *
-     * When name is changed, register iconset metadata
-     *
-     */
-    _nameChanged: function() {
-      new Polymer.IronMeta({type: 'iconset', key: this.name, value: this});
-      this.async(function() {
-        this.fire('iron-iconset-added', this, {node: window});
-      });
-    },
-
-    /**
-     * Create a map of child SVG elements by id.
-     *
-     * @return {!Object} Map of id's to SVG elements.
-     */
-    _createIconMap: function() {
-      // Objects chained to Object.prototype (`{}`) have members. Specifically,
-      // on FF there is a `watch` method that confuses the icon map, so we
-      // need to use a null-based object here.
-      var icons = Object.create(null);
-      Polymer.dom(this).querySelectorAll('[id]')
-        .forEach(function(icon) {
-          icons[icon.id] = icon;
-        });
-      return icons;
-    },
-
-    /**
-     * Produce installable clone of the SVG element matching `id` in this
-     * iconset, or `undefined` if there is no matching element.
-     *
-     * @return {Element} Returns an installable clone of the SVG element
-     * matching `id`.
-     */
-    _cloneIcon: function(id) {
-      // create the icon map on-demand, since the iconset itself has no discrete
-      // signal to know when it's children are fully parsed
-      this._icons = this._icons || this._createIconMap();
-      return this._prepareSvgClone(this._icons[id], this.size);
-    },
-
-    /**
-     * @param {Element} sourceSvg
-     * @param {number} size
-     * @return {Element}
-     */
-    _prepareSvgClone: function(sourceSvg, size) {
-      if (sourceSvg) {
-        var svg = document.createElementNS('http://www.w3.org/2000/svg', 'svg');
-        svg.setAttribute('viewBox', ['0', '0', size, size].join(' '));
-        svg.setAttribute('preserveAspectRatio', 'xMidYMid meet');
-        // TODO(dfreedm): `pointer-events: none` works around https://crbug.com/370136
-        // TODO(sjmiles): inline style may not be ideal, but avoids requiring a shadow-root
-        svg.style.cssText = 'pointer-events: none; display: block; width: 100%; height: 100%;';
-        svg.appendChild(sourceSvg.cloneNode(true)).removeAttribute('id');
-        return svg;
-      }
-      return null;
-    }
-
-  });
 Polymer({
       is: 'paper-item',
 
       hostAttributes: {
         role: 'listitem',
         tabindex: '0'
       },
 
       behaviors: [
         Polymer.IronControlState,
@@ skipping 191 matching lines @@
         value: null
       },
 
       /**
        * The set of excluded elements where the key is the `localName`
        * of the element that will be ignored from the item list.
        *
        * @type {object}
        * @default {template: 1}
        */
-      excludedLocalNames: {
+      _excludedLocalNames: {
         type: Object,
         value: function() {
           return {
             'template': 1
           };
         }
       }
     },
 
     observers: [
       '_updateSelected(attrForSelected, selected)'
     ],
 
     created: function() {
       this._bindFilterItem = this._filterItem.bind(this);
       this._selection = new Polymer.IronSelection(this._applySelection.bind(this));
+      // TODO(cdata): When polymer/polymer#2535 lands, we do not need to do this
+      // book keeping anymore:
+      this.__listeningForActivate = false;
     },
 
     attached: function() {
       this._observer = this._observeItems(this);
       this._contentObserver = this._observeContent(this);
       if (!this.selectedItem && this.selected) {
         this._updateSelected(this.attrForSelected,this.selected)
       }
+      this._addListener(this.activateEvent);
     },
 
     detached: function() {
       if (this._observer) {
         this._observer.disconnect();
       }
       if (this._contentObserver) {
         this._contentObserver.disconnect();
       }
       this._removeListener(this.activateEvent);
@@ skipping 46 matching lines @@
      * Selects the next item.
      *
      * @method selectNext
      */
     selectNext: function() {
       var index = (Number(this._valueToIndex(this.selected)) + 1) % this.items.length;
       this.selected = this._indexToValue(index);
     },
 
     _addListener: function(eventName) {
+      if (!this.isAttached || this.__listeningForActivate) {
+        return;
+      }
+
+      this.__listeningForActivate = true;
       this.listen(this, eventName, '_activateHandler');
     },
 
     _removeListener: function(eventName) {
       this.unlisten(this, eventName, '_activateHandler');
+      this.__listeningForActivate = false;
     },
 
     _activateEventChanged: function(eventName, old) {
       this._removeListener(old);
       this._addListener(eventName);
     },
 
     _updateSelected: function() {
       this._selectSelected(this.selected);
     },
 
     _selectSelected: function(selected) {
       this._selection.select(this._valueToItem(this.selected));
     },
 
     _filterItem: function(node) {
-      return !this.excludedLocalNames[node.localName];
+      return !this._excludedLocalNames[node.localName];
     },
 
     _valueToItem: function(value) {
       return (value == null) ? null : this.items[this._valueToIndex(value)];
     },
 
     _valueToIndex: function(value) {
       if (this.attrForSelected) {
         for (var i = 0, item; item = this.items[i]; i++) {
           if (this._valueForItem(item) == value) {
@@ skipping 490 matching lines @@
     is: 'paper-menu',
 
     behaviors: [
       Polymer.IronMenuBehavior
     ]
 
   });
 
 })();
 /**
-   * `IronResizableBehavior` is a behavior that can be used in Polymer elements to
-   * coordinate the flow of resize events between "resizers" (elements that control the
-   * size or hidden state of their children) and "resizables" (elements that need to be
-   * notified when they are resized or un-hidden by their parents in order to take
-   * action on their new measurements).
-   * Elements that perform measurement should add the `IronResizableBehavior` behavior to
-   * their element definition and listen for the `iron-resize` event on themselves.
-   * This event will be fired when they become showing after having been hidden,
-   * when they are resized explicitly by another resizable, or when the window has been
-   * resized.
-   * Note, the `iron-resize` event is non-bubbling.
-   *
-   * @polymerBehavior Polymer.IronResizableBehavior
-   * @demo demo/index.html
-   **/
-  Polymer.IronResizableBehavior = {
-    properties: {
-      /**
-       * The closest ancestor element that implements `IronResizableBehavior`.
-       */
-      _parentResizable: {
-        type: Object,
-        observer: '_parentResizableChanged'
-      },
-
-      /**
-       * True if this element is currently notifying its descedant elements of
-       * resize.
-       */
-      _notifyingDescendant: {
-        type: Boolean,
-        value: false
-      }
-    },
-
-    listeners: {
-      'iron-request-resize-notifications': '_onIronRequestResizeNotifications'
-    },
-
-    created: function() {
-      // We don't really need property effects on these, and also we want them
-      // to be created before the `_parentResizable` observer fires:
-      this._interestedResizables = [];
-      this._boundNotifyResize = this.notifyResize.bind(this);
-    },
-
-    attached: function() {
-      this.fire('iron-request-resize-notifications', null, {
-        node: this,
-        bubbles: true,
-        cancelable: true
-      });
-
-      if (!this._parentResizable) {
-        window.addEventListener('resize', this._boundNotifyResize);
-        this.notifyResize();
-      }
-    },
-
-    detached: function() {
-      if (this._parentResizable) {
-        this._parentResizable.stopResizeNotificationsFor(this);
-      } else {
-        window.removeEventListener('resize', this._boundNotifyResize);
-      }
-
-      this._parentResizable = null;
-    },
-
-    /**
-     * Can be called to manually notify a resizable and its descendant
-     * resizables of a resize change.
-     */
-    notifyResize: function() {
-      if (!this.isAttached) {
-        return;
-      }
-
-      this._interestedResizables.forEach(function(resizable) {
-        if (this.resizerShouldNotify(resizable)) {
-          this._notifyDescendant(resizable);
-        }
-      }, this);
-
-      this._fireResize();
-    },
-
-    /**
-     * Used to assign the closest resizable ancestor to this resizable
-     * if the ancestor detects a request for notifications.
-     */
-    assignParentResizable: function(parentResizable) {
-      this._parentResizable = parentResizable;
-    },
-
-    /**
-     * Used to remove a resizable descendant from the list of descendants
-     * that should be notified of a resize change.
-     */
-    stopResizeNotificationsFor: function(target) {
-      var index = this._interestedResizables.indexOf(target);
-
-      if (index > -1) {
-        this._interestedResizables.splice(index, 1);
-        this.unlisten(target, 'iron-resize', '_onDescendantIronResize');
-      }
-    },
-
-    /**
-     * This method can be overridden to filter nested elements that should or
-     * should not be notified by the current element. Return true if an element
-     * should be notified, or false if it should not be notified.
-     *
-     * @param {HTMLElement} element A candidate descendant element that
-     * implements `IronResizableBehavior`.
-     * @return {boolean} True if the `element` should be notified of resize.
-     */
-    resizerShouldNotify: function(element) { return true; },
-
-    _onDescendantIronResize: function(event) {
-      if (this._notifyingDescendant) {
-        event.stopPropagation();
-        return;
-      }
-
-      // NOTE(cdata): In ShadowDOM, event retargetting makes echoing of the
-      // otherwise non-bubbling event "just work." We do it manually here for
-      // the case where Polymer is not using shadow roots for whatever reason:
-      if (!Polymer.Settings.useShadow) {
-        this._fireResize();
-      }
-    },
-
-    _fireResize: function() {
-      this.fire('iron-resize', null, {
-        node: this,
-        bubbles: false
-      });
-    },
-
-    _onIronRequestResizeNotifications: function(event) {
-      var target = event.path ? event.path[0] : event.target;
-
-      if (target === this) {
-        return;
-      }
-
-      if (this._interestedResizables.indexOf(target) === -1) {
-        this._interestedResizables.push(target);
-        this.listen(target, 'iron-resize', '_onDescendantIronResize');
-      }
-
-      target.assignParentResizable(this);
-      this._notifyDescendant(target);
-
-      event.stopPropagation();
-    },
-
-    _parentResizableChanged: function(parentResizable) {
-      if (parentResizable) {
-        window.removeEventListener('resize', this._boundNotifyResize);
-      }
-    },
-
-    _notifyDescendant: function(descendant) {
-      // NOTE(cdata): In IE10, attached is fired on children first, so it's
-      // important not to notify them if the parent is not attached yet (or
-      // else they will get redundantly notified when the parent attaches).
-      if (!this.isAttached) {
-        return;
-      }
-
-      this._notifyingDescendant = true;
-      descendant.notifyResize();
-      this._notifyingDescendant = false;
-    }
-  };
-/**
 Polymer.IronFitBehavior fits an element in another element using `max-height` and `max-width`, and
 optionally centers it in the window or another element.
 
 The element will only be sized and/or positioned if it has not already been sized and/or positioned
 by CSS.
 
 CSS properties               | Action
 -----------------------------|-------------------------------------------
 `position` set               | Element is not centered horizontally or vertically
 `top` or `bottom` set        | Element is not vertically centered
@@ skipping 394 matching lines @@
 on top of other content. It includes an optional backdrop, and can be used to implement a variety
 of UI controls including dialogs and drop downs. Multiple overlays may be displayed at once.
 
 ### Closing and canceling
 
 A dialog may be hidden by closing or canceling. The difference between close and cancel is user
 intent. Closing generally implies that the user acknowledged the content on the overlay. By default,
 it will cancel whenever the user taps outside it or presses the escape key. This behavior is
 configurable with the `no-cancel-on-esc-key` and the `no-cancel-on-outside-click` properties.
 `close()` should be called explicitly by the implementer when the user interacts with a control
-in the overlay element.
+in the overlay element. When the dialog is canceled, the overlay fires an 'iron-overlay-canceled'
+event. Call `preventDefault` on this event to prevent the overlay from closing.
 
 ### Positioning
 
 By default the element is sized and positioned to fit and centered inside the window. You can
 position and size it manually using CSS. See `Polymer.IronFitBehavior`.
 
 ### Backdrop
 
 Set the `with-backdrop` attribute to display a backdrop behind the overlay. The backdrop is
 appended to `<body>` and is of type `<iron-overlay-backdrop>`. See its doc page for styling
@@ skipping 150 matching lines @@
      */
     close: function() {
       this.opened = false;
       this._setCanceled(false);
     },
 
     /**
      * Cancels the overlay.
      */
     cancel: function() {
+      var cancelEvent = this.fire('iron-overlay-canceled', undefined, {cancelable: true});
+      if (cancelEvent.defaultPrevented) {
+        return;
+      }
+
       this.opened = false;
       this._setCanceled(true);
     },
 
     _ensureSetup: function() {
       if (this._overlaySetup) {
         return;
       }
       this._overlaySetup = true;
       this.style.outline = 'none';
@@ skipping 1528 matching lines @@
     });
 
     PaperMenuButton.ANIMATION_CUBIC_BEZIER = 'cubic-bezier(.3,.95,.5,1)';
     PaperMenuButton.MAX_ANIMATION_TIME_MS = 400;
 
     Polymer.PaperMenuButton = PaperMenuButton;
   })();
 /**
    * `Polymer.PaperInkyFocusBehavior` implements a ripple when the element has keyboard focus.
    *
-   * @polymerBehavior Polymer.PaperInkyFocusBehavior
+   * @polymerBehavior Polymer.PaperInkyFocusBehaviorImpl
    */
   Polymer.PaperInkyFocusBehaviorImpl = {
 
     observers: [
       '_focusedChanged(receivedFocusFromKeyboard)'
     ],
 
     _focusedChanged: function(receivedFocusFromKeyboard) {
-      if (!this.$.ink) {
-        return;
+      if (receivedFocusFromKeyboard) {
+        this.ensureRipple();
       }
+      if (this.hasRipple()) {
+        this._ripple.holdDown = receivedFocusFromKeyboard;
+      }
+    },
 
-      this.$.ink.holdDown = receivedFocusFromKeyboard;
+    _createRipple: function() {
+      var ripple = Polymer.PaperRippleBehavior._createRipple();
+      ripple.id = 'ink';
+      ripple.setAttribute('center', '');
+      ripple.classList.add('circle');
+      return ripple;
     }
 
   };
 
   /** @polymerBehavior Polymer.PaperInkyFocusBehavior */
   Polymer.PaperInkyFocusBehavior = [
     Polymer.IronButtonState,
     Polymer.IronControlState,
+    Polymer.PaperRippleBehavior,
     Polymer.PaperInkyFocusBehaviorImpl
   ];
 Polymer({
-    is: 'paper-icon-button',
+      is: 'paper-icon-button',
 
-    hostAttributes: {
-      role: 'button',
-      tabindex: '0'
-    },
-
-    behaviors: [
-      Polymer.PaperInkyFocusBehavior
-    ],
-
-    properties: {
-      /**
-       * The URL of an image for the icon. If the src property is specified,
-       * the icon property should not be.
-       */
-      src: {
-        type: String
+      hostAttributes: {
+        role: 'button',
+        tabindex: '0'
       },
 
-      /**
-       * Specifies the icon name or index in the set of icons available in
-       * the icon's icon set. If the icon property is specified,
-       * the src property should not be.
-       */
-      icon: {
-        type: String
+      behaviors: [
+        Polymer.PaperInkyFocusBehavior
+      ],
+
+      properties: {
+        /**
+         * The URL of an image for the icon. If the src property is specified,
+         * the icon property should not be.
+         */
+        src: {
+          type: String
+        },
+
+        /**
+         * Specifies the icon name or index in the set of icons available in
+         * the icon's icon set. If the icon property is specified,
+         * the src property should not be.
+         */
+        icon: {
+          type: String
+        },
+
+        /**
+         * Specifies the alternate text for the button, for accessibility.
+         */
+        alt: {
+          type: String,
+          observer: "_altChanged"
+        }
       },
 
-      /**
-       * Specifies the alternate text for the button, for accessibility.
-       */
-      alt: {
-        type: String,
-        observer: "_altChanged"
+      _altChanged: function(newValue, oldValue) {
+        var label = this.getAttribute('aria-label');
+
+        // Don't stomp over a user-set aria-label.
+        if (!label || oldValue == label) {
+          this.setAttribute('aria-label', newValue);
+        }
       }
-    },
-
-    _altChanged: function(newValue, oldValue) {
-      var label = this.getAttribute('aria-label');
-
-      // Don't stomp over a user-set aria-label.
-      if (!label || oldValue == label) {
-        this.setAttribute('aria-label', newValue);
-      }
-    }
-  });
+    });
 /**
    * Use `Polymer.IronValidatableBehavior` to implement an element that validates user input.
    *
    * ### Accessibility
    *
    * Changing the `invalid` property, either manually or by calling `validate()` will update the
    * `aria-invalid` attribute.
    *
    * @demo demo/index.html
    * @polymerBehavior
@@ skipping 777 matching lines @@
 
 cr.define('downloads', function() {
   var Manager = Polymer({
     is: 'downloads-manager',
 
     properties: {
       hasDownloads_: {
         type: Boolean,
         value: false,
       },
+
+      items_: {
+        type: Array,
+      },
     },
 
     /**
-     * @return {number} A guess at how many items could be visible at once.
-     * @private
-     */
-    guesstimateNumberOfVisibleItems_: function() {
-      var toolbarHeight = this.$.toolbar.offsetHeight;
-      return Math.floor((window.innerHeight - toolbarHeight) / 46) + 1;
-    },
-
-    /**
      * @param {Event} e
      * @private
      */
     onCanExecute_: function(e) {
       e = /** @type {cr.ui.CanExecuteEvent} */(e);
       switch (e.command.id) {
         case 'undo-command':
           e.canExecute = this.$.toolbar.canUndo();
           break;
         case 'clear-all-command':
@@ skipping 16 matching lines @@
     /** @private */
     onLoad_: function() {
       cr.ui.decorate('command', cr.ui.Command);
       document.addEventListener('canExecute', this.onCanExecute_.bind(this));
       document.addEventListener('command', this.onCommand_.bind(this));
 
       // Shows all downloads.
       downloads.ActionService.getInstance().search('');
     },
 
-    /** @private */
-    rebuildFocusGrid_: function() {
-      var activeElement = this.shadowRoot.activeElement;
-
-      var activeItem;
-      if (activeElement && activeElement.tagName == 'downloads-item')
-        activeItem = activeElement;
-
-      var activeControl = activeItem && activeItem.shadowRoot.activeElement;
-
-      /** @private {!cr.ui.FocusGrid} */
-      this.focusGrid_ = this.focusGrid_ || new cr.ui.FocusGrid;
-      this.focusGrid_.destroy();
-
-      var boundary = this.$['downloads-list'];
-
-      this.items_.forEach(function(item) {
-        var focusRow = new downloads.FocusRow(item.content, boundary);
-        this.focusGrid_.addRow(focusRow);
-
-        if (item == activeItem && !cr.ui.FocusRow.isFocusable(activeControl))
-          focusRow.getEquivalentElement(activeControl).focus();
-      }, this);
-
-      this.focusGrid_.ensureRowActive();
-    },
-
     /**
      * @return {number} The number of downloads shown on the page.
      * @private
      */
     size_: function() {
       return this.items_.length;
     },
 
     /**
      * Called when all items need to be updated.
      * @param {!Array<!downloads.Data>} list A list of new download data.
      * @private
      */
     updateAll_: function(list) {
-      var oldIdMap = this.idMap_ || {};
+      /** @private {!Object<number>} */
+      this.idToIndex_ = {};
 
-      /** @private {!Object<!downloads.Item>} */
-      this.idMap_ = {};
-
-      /** @private {!Array<!downloads.Item>} */
-      this.items_ = [];
-
-      if (!this.iconLoader_) {
-        var guesstimate = Math.max(this.guesstimateNumberOfVisibleItems_(), 1);
-        /** @private {downloads.ThrottledIconLoader} */
-        this.iconLoader_ = new downloads.ThrottledIconLoader(guesstimate);
-      }
+      var items = [];
 
       for (var i = 0; i < list.length; ++i) {
         var data = list[i];
         var id = data.id;
 
-        // Re-use old items when possible (saves work, preserves focus).
-        var item = oldIdMap[id] || new downloads.Item(this.iconLoader_);
+        this.idToIndex_[id] = i;
 
-        this.idMap_[id] = item;  // Associated by ID for fast lookup.
-        this.items_.push(item);  // Add to sorted list for order.
+        var prev = list[i - 1];
 
-        // Render |item| but don't actually add to the DOM yet. |this.items_|
-        // must be fully created to be able to find the right spot to insert.
-        item.update(data);
-
-        // Collapse redundant dates.
-        var prev = list[i - 1];
-        item.hideDate = !!prev && prev.date_string == data.date_string;
-
-        delete oldIdMap[id];
+        items.push({
+          index: i,
+          item: data,
+          hideDate: !!prev && prev.date_string == data.date_string,
+        });
       }
 
-      // Remove stale, previously rendered items from the DOM.
-      for (var id in oldIdMap) {
-        if (oldIdMap[id].parentNode)
-          oldIdMap[id].parentNode.removeChild(oldIdMap[id]);
-        delete oldIdMap[id];
-      }
-
-      for (var i = 0; i < this.items_.length; ++i) {
-        var item = this.items_[i];
-        if (item.parentNode)  // Already in the DOM; skip.
-          continue;
-
-        var before = null;
-        // Find the next rendered item after this one, and insert before it.
-        for (var j = i + 1; !before && j < this.items_.length; ++j) {
-          if (this.items_[j].parentNode)
-            before = this.items_[j];
-        }
-        // If |before| is null, |item| will just get added at the end.
-        this.$['downloads-list'].insertBefore(item, before);
-      }
+      // TODO(dbeam): this is a huge hack. Let's figure out a better way.
+      var resetScrollPosition = this.$['downloads-list']._resetScrollPosition;
+      this.$['downloads-list']._resetScrollPosition = function() {};
+      this.items_ = items;
+      this.$['downloads-list']._resetScrollPosition = resetScrollPosition;
 
       var hasDownloads = this.size_() > 0;
       if (!hasDownloads) {
         var isSearching = downloads.ActionService.getInstance().isSearching();
         var messageToShow = isSearching ? 'noSearchResults' : 'noDownloads';
         this.$['no-downloads'].querySelector('span').textContent =
             loadTimeData.getString(messageToShow);
       }
       this.hasDownloads_ = hasDownloads;
 
       if (loadTimeData.getBoolean('allowDeletingHistory'))
         this.$.toolbar.downloadsShowing = this.hasDownloads_;
 
       this.$.panel.classList.remove('loading');
-
-      var allReady = this.items_.map(function(i) { return i.readyPromise; });
-      Promise.all(allReady).then(this.rebuildFocusGrid_.bind(this));
     },
 
     /**
      * @param {!downloads.Data} data
      * @private
      */
     updateItem_: function(data) {
-      var item = this.idMap_[data.id];
-
-      var activeControl = this.shadowRoot.activeElement == item ?
-          item.shadowRoot.activeElement : null;
-
-      item.update(data);
-
-      this.async(function() {
-        if (activeControl && !cr.ui.FocusRow.isFocusable(activeControl)) {
-          var focusRow = this.focusGrid_.getRowForRoot(item.content);
-          focusRow.getEquivalentElement(activeControl).focus();
-        }
-      }.bind(this));
+      var index = this.idToIndex_[data.id];
+      this.set('items_.' + index + '.item', data);
+      this.$['downloads-list'].updateSizeForItem(index);
     },
   });
 
   Manager.size = function() {
     return document.querySelector('downloads-manager').size_();
   };
 
   Manager.updateAll = function(list) {
     document.querySelector('downloads-manager').updateAll_(list);
   };
 
   Manager.updateItem = function(item) {
     document.querySelector('downloads-manager').updateItem_(item);
   };
 
   Manager.onLoad = function() {
     document.querySelector('downloads-manager').onLoad_();
   };
 
   return {Manager: Manager};
 });
 
 window.addEventListener('load', downloads.Manager.onLoad);