Fixing iframe jank in the local omnibox popup.

chrome/browser/resources/local_omnibox_popup/local_omnibox_popup.js

 // Copyright 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.
 
 /**
  * @fileoverview Support for omnibox behavior in offline mode or when API
  * features are not supported on the server.
  */
-
-// ==========================================================
-//  Enums.
-// ==========================================================
+(function() {
+<include src="../../../../ui/webui/resources/js/assert.js">
 
 /**
  * Possible behaviors for navigateContentWindow.
  * @enum {number}
  */
 var WindowOpenDisposition = {
   CURRENT_TAB: 1,
   NEW_BACKGROUND_TAB: 2
 };
 
 /**
  * The JavaScript button event value for a middle click.
  * @type {number}
  * @const
  */
 var MIDDLE_MOUSE_BUTTON = 1;
 
-// =============================================================================
-//                               Util functions
-// =============================================================================
-
 /**
  * The maximum number of suggestions to show.
  * @type {number}
  * @const
  */
 var MAX_SUGGESTIONS_TO_SHOW = 5;
 
 /**
  * Assume any native suggestion with a score higher than this value has been
  * inlined by the browser.
  * @type {number}
  * @const
  */
 var INLINE_SUGGESTION_THRESHOLD = 1200;
 
 /**
+ * The color code for a query.
+ * @type {number}
+ * @const
+ */
+var QUERY_COLOR = 0x000000;
+
+/**
+ * The color code for a display URL.
+ * @type {number}
+ * @const
+ */
+var URL_COLOR = 0x009933;
+
+/**
+ * The color code for a suggestion title.
+ * @type {number}
+ * @const
+ */
+var TITLE_COLOR = 0x666666;
+
+/**
+ * A top position which is off-screen.
+ * @type {string}
+ * @const
+ */
+var OFF_SCREEN = '-1000px';
+
+/**
+ * The expected origin of a suggestion iframe.
+ * @type {string}
+ * @const
+ */
+var SUGGESTION_ORIGIN = 'chrome-search://suggestion';
+
+/**
  * Suggestion provider type corresponding to a verbatim URL suggestion.
  * @type {string}
  * @const
  */
 var VERBATIM_URL_TYPE = 'url-what-you-typed';
 
 /**
  * Suggestion provider type corresponding to a verbatim search suggestion.
  * @type {string}
  * @const
  */
 var VERBATIM_SEARCH_TYPE = 'search-what-you-typed';
 
 /**
- * The omnibox input value during the last onnativesuggestions event.
- * @type {string}
+ * "Up" arrow keycode.
+ * @type {number}
+ * @const
  */
-var lastInputValue = '';
+var KEY_UP_ARROW = 38;
 
 /**
- * The ordered restricted ids of the currently displayed suggestions.  Since the
- * suggestions contain the user's personal data (browser history) the searchBox
- * API embeds the content of the suggestion in a shadow dom, and assigns a
- * random restricted id to each suggestion which is accessible to the JS.
- * @type {Array.<number>}
+ * "Down" arrow keycode.
+ * @type {number}
+ * @const
  */
-
-var restrictedIds = [];
+var KEY_DOWN_ARROW = 40;
 
 /**
- * The index of the currently selected suggestion or -1 if none are selected.
+ * Pixels of padding inside a suggestion div for displaying its icon.
+ * @type {number}
+ * @const
+ */
+var SUGGESTION_ICON_PADDING = 26;
+
+/**
+ * Pixels by which iframes should be moved down relative to their wrapping
+ * suggestion div.
+ */
+var SUGGESTION_TOP_OFFSET = 4;
+
+/**
+ * The displayed suggestions.
+ * @type {SuggestionsBox}
+ */
+var activeBox;
+
+/**
+ * The suggestions being rendered.
+ * @type {SuggestionsBox}
+ */
+var pendingBox;
+
+/**
+ * A pool of iframes to display suggestions.
+ * @type {IframePool}
+ */
+var iframePool;
+
+/**
+ * A serial number for the next suggestions rendered.
  * @type {number}
  */
-var selectedIndex = -1;
+var nextRequestId = 0;
 
 /**
- * Shortcut for document.getElementById.
- * @param {string} id of the element.
- * @return {HTMLElement} with the id.
+ * Shortcut for document.querySelector.
+ * @param {string} selector A selector to query the desired element.
+ * @return {HTMLElement} The first element to match |selector| or null.
  */
-function $(id) {
-  return document.getElementById(id);
+function $qs(selector) {
+  return document.querySelector(selector);
 }
 
 /**
- * Displays a suggestion.
- * @param {Object} suggestion The suggestion to render.
- * @param {HTMLElement} box The html element to add the suggestion to.
- * @param {boolean} select True to select the selection.
- */
-function addSuggestionToBox(suggestion, box, select) {
-  var suggestionDiv = document.createElement('div');
-  suggestionDiv.classList.add('suggestion');
-  suggestionDiv.classList.toggle('selected', select);
-  suggestionDiv.classList.toggle('search', suggestion.is_search);
-
-  if (suggestion.destination_url) {  // iframes.
-    var suggestionIframe = document.createElement('iframe');
-    suggestionIframe.className = 'contents';
-    suggestionIframe.src = suggestion.destination_url;
-    suggestionIframe.id = suggestion.rid;
-    suggestionDiv.appendChild(suggestionIframe);
-  } else {
-    var contentsContainer = document.createElement('div');
-    var contents = suggestion.combinedNode;
-    contents.classList.add('contents');
-    contentsContainer.appendChild(contents);
-    suggestionDiv.appendChild(contentsContainer);
-    suggestionDiv.onclick = function(event) {
-      handleSuggestionClick(suggestion.rid, event.button);
-    };
-  }
-
-  restrictedIds.push(suggestion.rid);
-  box.appendChild(suggestionDiv);
-}
-
-/**
- * Renders the input suggestions.
- * @param {Array} nativeSuggestions An array of native suggestions to render.
- */
-function renderSuggestions(nativeSuggestions) {
-  var box = document.createElement('div');
-  box.id = 'suggestionsBox';
-  $('suggestions-box-container').appendChild(box);
-
-  for (var i = 0, length = nativeSuggestions.length;
-       i < Math.min(MAX_SUGGESTIONS_TO_SHOW, length); ++i) {
-    // Don't add the search-what-you-typed suggestion if it's the top match.
-    if (i > 0 || nativeSuggestions[i].type != VERBATIM_SEARCH_TYPE)
-      addSuggestionToBox(nativeSuggestions[i], box, i == selectedIndex);
-  }
-}
-
-/**
- * Clears the suggestions being displayed.
- */
-function clearSuggestions() {
-  $('suggestions-box-container').innerHTML = '';
-  restrictedIds = [];
-  selectedIndex = -1;
-}
-
-/**
- * @return {number} The height of the dropdown.
- */
-function getDropdownHeight() {
-  return $('suggestions-box-container').offsetHeight;
-}
-
-/**
  * @param {Object} suggestion A suggestion.
  * @param {boolean} inVerbatimMode Are we in verbatim mode?
  * @return {boolean} True if the suggestion should be selected.
  */
 function shouldSelectSuggestion(suggestion, inVerbatimMode) {
   var isVerbatimUrl = suggestion.type == VERBATIM_URL_TYPE;
-  var inlinableSuggestion = suggestion.type != VERBATIM_SEARCH_TYPE &&
+  var inlineableSuggestion = suggestion.type != VERBATIM_SEARCH_TYPE &&
       suggestion.rankingData.relevance > INLINE_SUGGESTION_THRESHOLD;
   // Verbatim URLs should always be selected. Otherwise, select suggestions
   // with a high enough score unless we are in verbatim mode (e.g. backspacing
   // away).
-  return isVerbatimUrl || (!inVerbatimMode && inlinableSuggestion);
-}
-
-/**
- * Updates selectedIndex, bounding it between -1 and the total number of
- * of suggestions - 1 (looping as necessary), and selects the corresponding
- * suggestion.
- * @param {boolean} increment True to increment the selected suggestion, false
- *     to decrement.
- */
-function updateSelectedSuggestion(increment) {
-  var numSuggestions = restrictedIds.length;
-  if (!numSuggestions)
-    return;
-
-  var oldSelection = $('suggestionsBox').querySelector('.selected');
-  if (oldSelection)
-    oldSelection.classList.remove('selected');
-
-  if (increment)
-    selectedIndex = ++selectedIndex > numSuggestions - 1 ? -1 : selectedIndex;
-  else
-    selectedIndex = --selectedIndex < -1 ? numSuggestions - 1 : selectedIndex;
-  var apiHandle = getApiObjectHandle();
-  if (selectedIndex == -1) {
-    apiHandle.setValue(lastInputValue);
+  return isVerbatimUrl || (!inVerbatimMode && inlineableSuggestion);
+}
+
+/**
+ * Extract the desired navigation behavior from a click button.
+ * @param {number} button The Event#button property of a click event.
+ * @return {WindowOpenDisposition} The desired behavior for
+ *     navigateContentWindow.
+ */
+function getDispositionFromClickButton(button) {
+  if (button == MIDDLE_MOUSE_BUTTON)
+    return WindowOpenDisposition.NEW_BACKGROUND_TAB;
+  return WindowOpenDisposition.CURRENT_TAB;
+}
+
+
+/**
+ * Manages a pool of chrome-search suggestion result iframes.
+ * @constructor
+ */
+function IframePool() {
+}
+
+IframePool.prototype = {
+  /**
+   * HTML iframe elements.
+   * @type {Array.<Element>}
+   * @private
+   */
+  iframes_: [],
+
+  /**
+   * Initializes the pool with blank result template iframes, positioned off
+   * screen.
+   */
+  init: function() {
+    for (var i = 0; i < 2 * MAX_SUGGESTIONS_TO_SHOW; ++i) {
+      var iframe = document.createElement('iframe');
+      iframe.className = 'contents';
+      iframe.id = 'suggestion-text-' + i;
+      iframe.src = 'chrome-search://suggestion/result.html';
+      iframe.style.top = OFF_SCREEN;
+      iframe.addEventListener('mouseover', function(e) {
+        if (activeBox)
+          activeBox.hover(e.currentTarget.id);
+      }, false);
+      iframe.addEventListener('mouseout', function(e) {
+        if (activeBox)
+          activeBox.unhover(e.currentTarget.id);
+      }, false);
+      document.body.appendChild(iframe);
+      this.iframes_.push(iframe);
+    }
+  },
+
+  /**
+   * Reserves a free suggestion iframe from the pool.
+   * @return {Element} An iframe suitable for holding a suggestion.
+   */
+  reserve: function() {
+    return this.iframes_.pop();
+  },
+
+  /**
+   * Releases a suggestion iframe back into the pool.
+   * @param {Element} iframe The iframe to return to the pool.
+   */
+  release: function(iframe) {
+    this.iframes_.push(iframe);
+    iframe.style.top = OFF_SCREEN;
+  },
+};
+
+
+/**
+ * An individual suggestion.
+ * @param {!Object} data Autocomplete fields for this suggestion.
+ * @constructor
+ */
+function Suggestion(data) {
+  assert(data);
+  /**
+   * Autocomplete fields for this suggestion.
+   * @type {!Object}
+   * @private
+   */
+  this.data_ = data;
+}
+
+Suggestion.prototype = {
+  /**
+   * Releases the iframe reserved for this suggestion.
+   */
+  destroy: function() {
+    if (this.iframe_)
+      iframePool.release(this.iframe_);
+  },
+
+  /**
+   * Creates and appends the placeholder div for this suggestion to box.
+   * @param {Element} box A suggestions box.
+   * @param {boolean} selected True if the suggestion should be drawn as
+   *     selected and false otherwise.
+   */
+  appendToBox: function(box, selected) {
+    var div = document.createElement('div');
+    div.classList.add('suggestion');
+    div.classList.toggle('selected', selected);
+    div.classList.toggle('search', this.data_.is_search);
+    box.appendChild(div);
+    this.div_ = div;
+  },
+
+  /**
+   * Repositions the suggestion iframe to align with its expected dropdown
+   * position.
+   * @param {boolean} isRtl True if rendering right-to-left and false if not.
+   * @param {number} startMargin Leading space before suggestion.
+   * @param {number} totalMargin Total non-content space on suggestion line.
+   */
+  reposition: function(isRtl, startMargin, totalMargin) {
+    // Add in the expected parent offset and the top margin.
+    this.iframe_.style.top = this.div_.offsetTop + SUGGESTION_TOP_OFFSET + 'px';
+    // Call parseInt to enforce that startMargin and totalMargin are really
+    // numbers since we're interpolating CSS.
+    startMargin = parseInt(startMargin, 10);
+    totalMargin = parseInt(totalMargin, 10);
+    if (isFinite(startMargin) && isFinite(totalMargin)) {
+      this.iframe_.style[isRtl ? 'right' : 'left'] = startMargin + 'px';
+      this.iframe_.style.width = '-webkit-calc(100% - ' +
+          (totalMargin + SUGGESTION_ICON_PADDING) + 'px)';
+    }
+  },
+
+  /**
+   * Updates the suggestion selection state.
+   * @param {boolean} selected True if drawn selected or false if not.
+   */
+  select: function(selected) {
+    this.div_.classList.toggle('selected', selected);
+  },
+
+  /**
+   * Updates the suggestion hover state.
+   * @param {boolean} hovered True if drawn hovered or false if not.
+   */
+  hover: function(hovered) {
+    this.div_.classList.toggle('hovered', hovered);
+  },
+
+  /**
+   * @param {Window} iframeWindow The content window of an iframe.
+   * @return {boolean} True if this suggestion's iframe has the specified
+   *     window and false if not.
+   */
+  hasIframeWindow: function(iframeWindow) {
+    return this.iframe_.contentWindow == iframeWindow;
+  },
+
+  /**
+   * @param {string} id An element id.
+   * @return {boolean} True if this suggestion's iframe has the specified id
+   *     and false if not.
+   */
+  hasIframeId: function(id) {
+    return this.iframe_.id == id;
+  },
+
+  /**
+   * The iframe element for this suggestion.
+   * @type {Element}
+   */
+  set iframe(iframe) {
+    this.iframe_ = iframe;
+  },
+
+  /**
+   * The restricted id associated with this suggestion.
+   * @type {number}
+   */
+  get restrictedId() {
+    return this.data_.rid;
+  },
+};
+
+
+/**
+ * Displays a suggestions box.
+ * @param {string} inputValue The user text that prompted these suggestions.
+ * @param {!Array.<!Object>} suggestionData Suggestion data to display.
+ * @param {number} selectedIndex The index of the suggestion selected.
+ * @constructor
+ */
+function SuggestionsBox(inputValue, suggestionData, selectedIndex) {
+  /**
+   * The user text that prompted these suggestions.
+   * @type {string}
+   * @private
+   */
+  this.inputValue_ = inputValue;
+
+  /**
+   * The index of the suggestion currently selected, whether by default or
+   * because the user arrowed down to it.
+   * @type {number}
+   * @private
+   */
+  this.selectedIndex_ = selectedIndex;
+
+  /**
+   * The index of the suggestion currently under the mouse pointer.
+   * @type {number}
+   * @private
+   */
+  this.hoveredIndex_ = -1;
+
+  /**
+   * A stamp to distinguish this suggestions box from others.
+   * @type {number}
+   * @private
+   */
+  this.requestId_ = nextRequestId++;
+
+  /**
+   * The ordered suggestions this box is displaying.
+   * @type {Array.<Suggestion>}
+   * @private
+   */
+  this.suggestions_ = [];
+  for (var i = 0; i < suggestionData.length; ++i) {
+    this.suggestions_.push(new Suggestion(suggestionData[i]));
+  }
+
+  /**
+   * An embedded search API handle.
+   * @type {Object}
+   * @private
+   */
+  this.apiHandle_ = getApiObjectHandle();
+
+  /**
+   * The container for this suggestions box. div.pending-container if inactive
+   * and div.active-container if active.
+   * @type {Element}
+   * @private
+   */
+  this.container_ = $qs('.pending-container');
+  assert(this.container_);
+}
+
+SuggestionsBox.prototype = {
+  /**
+   * Releases suggestion iframes and ignores any load done message for the
+   * current suggestions.
+   */
+  destroy: function() {
+    while (this.suggestions_.length > 0) {
+      this.suggestions_.pop().destroy();
+    }
+    this.responseId = -1;
+  },
+
+  /**
+   * Starts rendering new suggestions.
+   */
+  loadSuggestions: function() {
+    // Create a placeholder DOM in the invisible container.
+    this.container_.innerHTML = '';
+
+    var box = document.createElement('div');
+    box.className = 'suggestions-box';
+    this.container_.appendChild(box);
+
+    var iframesToLoad = {};
+    for (var i = 0; i < this.suggestions_.length; ++i) {
+      var suggestion = this.suggestions_[i];
+      suggestion.appendToBox(box, i == this.selectedIndex_);
+      var iframe = iframePool.reserve();
+      suggestion.iframe = iframe;
+      iframesToLoad[iframe.id] = suggestion.restrictedId;
+    }
+
+    // Ask the loader iframe to populate the iframes just reserved.
+    var loadRequest = {
+      load: iframesToLoad,
+      requestId: this.requestId_,
+      style: {
+        queryColor: QUERY_COLOR,
+        urlColor: URL_COLOR,
+        titleColor: TITLE_COLOR
+      }
+    };
+    $qs('#suggestion-loader').contentWindow.postMessage(loadRequest,
+        SUGGESTION_ORIGIN);
+  },
+
+  /**
+   * @param {number} responseId The id of a request that just finished
+   *     rendering.
+   * @return {boolean} Whether the request is for the suggestions in this box.
+   */
+  isResponseCurrent: function(responseId) {
+    return responseId == this.requestId_;
+  },
+
+  /**
+   * Moves suggestion iframes into position.
+   */
+  repositionSuggestions: function() {
+    // Note: This may be called before margins are ready. In that case,
+    // suggestion iframes will initially be too large and then size down
+    // onresize.
+    var startMargin = this.apiHandle_.startMargin;
+    var totalMargin = window.innerWidth - this.apiHandle_.width;
+    var isRtl = this.apiHandle_.isRtl;
+    for (var i = 0; i < this.suggestions_.length; ++i) {
+      this.suggestions_[i].reposition(isRtl, startMargin, totalMargin);
+    }
+  },
+
+  /**
+   * Selects the suggestion before the current selection.
+   */
+  selectPrevious: function() {
+    this.changeSelection_(this.selectedIndex_ - 1);
+  },
+
+  /**
+   * Selects the suggestion after the current selection.
+   */
+  selectNext: function() {
+    this.changeSelection_(this.selectedIndex_ + 1);
+  },
+
+  /**
+   * Changes the current selected suggestion index.
+   * @param {number} index The new selection to suggest.
+   * @private
+   */
+  changeSelection_: function(index) {
+    var numSuggestions = this.suggestions_.length;
+    this.selectedIndex_ = Math.min(numSuggestions - 1, Math.max(-1, index));
+
+    this.redrawSelection_();
+    this.redrawHover_();
+  },
+
+  /**
+   * Redraws the selected suggestion.
+   * @private
+   */
+  redrawSelection_: function() {
+    var oldSelection = this.container_.querySelector('.selected');
+    if (oldSelection)
+      oldSelection.classList.remove('selected');
+    if (this.selectedIndex_ == -1) {
+      this.apiHandle_.setValue(this.inputValue_);
+    } else {
+      this.suggestions_[this.selectedIndex_].select(true);
+      this.apiHandle_.setRestrictedValue(
+          this.suggestions_[this.selectedIndex_].restrcitedId);
+    }
+  },
+
+  /**
+   * Returns the restricted id of the iframe clicked.
+   * @param {!Window} iframeWindow The window of the iframe that was clicked.
+   * @return {?number} The restricted id clicked or null if none.
+   */
+  getClickTarget: function(iframeWindow) {
+    for (var i = 0; i < this.suggestions_.length; ++i) {
+      if (this.suggestions_[i].hasIframeWindow(iframeWindow))
+        return this.suggestions_[i].restrictedId;
+    }
+    return null;
+  },
+
+  /**
+   * Called when the user hovers on the specified iframe.
+   * @param {string} iframeId The id of the iframe hovered.
+   */
+  hover: function(iframeId) {
+    this.hoveredIndex_ = -1;
+    for (var i = 0; i < this.suggestions_.length; ++i) {
+      if (this.suggestions_[i].hasIframeId(iframeId)) {
+        this.hoveredIndex_ = i;
+        break;
+      }
+    }
+    this.redrawHover_();
+  },
+
+  /**
+   * Called when the user unhovers the specified iframe.
+   * @param {string} iframeId The id of the iframe hovered.
+   */
+  unhover: function(iframeId) {
+    if (this.suggestions_[this.hoveredIndex_] &&
+        this.suggestions_[this.hoveredIndex_].hasIframeId(iframeId)) {
+      this.clearHover();
+    }
+  },
+
+  /**
+   * Clears the current hover.
+   */
+  clearHover: function() {
+    this.hoveredIndex_ = -1;
+    this.redrawHover_();
+  },
+
+  /**
+   * Redraws the mouse hover background.
+   * @private
+   */
+  redrawHover_: function() {
+    var oldHover = this.container_.querySelector('.hovered');
+    if (oldHover)
+      oldHover.classList.remove('hovered');
+    if (this.hoveredIndex_ != -1 && this.hoveredIndex_ != this.selectedIndex_)
+      this.suggestions_[this.hoveredIndex_].hover(true);
+  },
+
+  /**
+   * Marks the suggestions container as active.
+   */
+  activate: function() {
+    this.container_.className = 'active-container';
+  },
+
+  /**
+   * Marks the suggestions container as inactive.
+   */
+  deactivate: function() {
+    this.container_.className = 'pending-container';
+    this.container_.innerHTML = '';
+  },
+
+  /**
+   * The height of the suggestions container.
+   * @type {number}
+   */
+  get height() {
+    return this.container_.offsetHeight;
+  },
+};
+
+
+/**
+ * Clears the currently active suggestions and shows pending suggestions.
+ */
+function makePendingSuggestionsActive() {
+  if (activeBox) {
+    activeBox.deactivate();
+    activeBox.destroy();
   } else {
-    var newSelection = $('suggestionsBox').querySelector(
-        '.suggestion:nth-of-type(' + (selectedIndex + 1) + ')');
-    newSelection.classList.add('selected');
-    apiHandle.setRestrictedValue(restrictedIds[selectedIndex]);
+    // Initially there will be no active suggestions, but we still want to use
+    // div.active-container to load the next suggestions.
+    $qs('.active-container').className = 'pending-container';
   }
-}
-
-// =============================================================================
-//                             Handlers / API stuff
-// =============================================================================
+  pendingBox.activate();
+  activeBox = pendingBox;
+  pendingBox = null;
+  activeBox.repositionSuggestions();
+  getApiObjectHandle().showOverlay(activeBox.height);
+}
+
+/**
+ * Hides the active suggestions box.
+ */
+function hideActiveSuggestions() {
+  getApiObjectHandle().showOverlay(0);
+  if (activeBox) {
+    $qs('.active-container').innerHTML = '';
+    activeBox.destroy();
+  }
+  activeBox = null;
+}
 
 /**
  * @return {Object} the handle to the searchBox API.
  */
- function getApiObjectHandle() {
+function getApiObjectHandle() {
   if (window.cideb)
     return window.cideb;
   if (window.navigator && window.navigator.embeddedSearch &&
       window.navigator.embeddedSearch.searchBox)
     return window.navigator.embeddedSearch.searchBox;
   if (window.chrome && window.chrome.embeddedSearch &&
       window.chrome.embeddedSearch.searchBox)
     return window.chrome.embeddedSearch.searchBox;
   return null;
 }
 
 /**
  * Updates suggestions in response to a onchange or onnativesuggestions call.
  */
 function updateSuggestions() {
+  if (pendingBox)
+    pendingBox.destroy();
+  pendingBox = null;
   var apiHandle = getApiObjectHandle();
-  lastInputValue = apiHandle.value;
-
-  clearSuggestions();
-  var nativeSuggestions = apiHandle.nativeSuggestions;
-  if (nativeSuggestions.length) {
-    nativeSuggestions.sort(function(a, b) {
+  var suggestions = apiHandle.nativeSuggestions;
+  if (suggestions.length) {
+    suggestions.sort(function(a, b) {
       return b.rankingData.relevance - a.rankingData.relevance;
     });
-    if (shouldSelectSuggestion(nativeSuggestions[0], apiHandle.verbatim))
+    var selectedIndex = -1;
+    if (shouldSelectSuggestion(suggestions[0], apiHandle.verbatim))
       selectedIndex = 0;
-    renderSuggestions(nativeSuggestions);
+    // Don't display a search-what-you-typed suggestion if it's the top match.
+    if (suggestions[0].type == VERBATIM_SEARCH_TYPE)
+      suggestions.shift();
   }
-
-  var height = getDropdownHeight();
-  apiHandle.showOverlay(height);
+  var inputValue = apiHandle.value;
+  if (!!inputValue && suggestions.length) {
+    pendingBox = new SuggestionsBox(inputValue,
+        suggestions.slice(0, MAX_SUGGESTIONS_TO_SHOW), selectedIndex);
+    pendingBox.loadSuggestions();
+  } else {
+    hideActiveSuggestions();
+  }
 }
 
 /**
  * Appends a style node for suggestion properties that depend on apiHandle.
  */
 function appendSuggestionStyles() {
   var apiHandle = getApiObjectHandle();
   var isRtl = apiHandle.rtl;
   var startMargin = apiHandle.startMargin;
   var style = document.createElement('style');
   style.type = 'text/css';
   style.id = 'suggestionStyle';
   style.textContent =
       '.suggestion, ' +
       '.suggestion.search {' +
       '  background-position: ' +
           (isRtl ? '-webkit-calc(100% - 5px)' : '5px') + ' 4px;' +
       '  -webkit-margin-start: ' + startMargin + 'px;' +
       '  -webkit-margin-end: ' +
           (window.innerWidth - apiHandle.width - startMargin) + 'px;' +
       '  font: ' + apiHandle.fontSize + 'px "' + apiHandle.font + '";' +
       '}';
-  document.querySelector('head').appendChild(style);
+  $qs('head').appendChild(style);
+  if (activeBox)
+    activeBox.repositionSuggestions();
   window.removeEventListener('resize', appendSuggestionStyles);
 }
 
 /**
- * Extract the desired navigation behavior from a click button.
- * @param {number} button The Event#button property of a click event.
- * @return {WindowOpenDisposition} The desired behavior for
- *     navigateContentWindow.
- */
-function getDispositionFromClickButton(button) {
-  if (button == MIDDLE_MOUSE_BUTTON)
-    return WindowOpenDisposition.NEW_BACKGROUND_TAB;
-  return WindowOpenDisposition.CURRENT_TAB;
-}
-
-/**
- * Handles suggestion clicks.
- * @param {number} restrictedId The restricted id of the suggestion being
- *     clicked.
- * @param {number} button The Event#button property of a click event.
- *
- */
-function handleSuggestionClick(restrictedId, button) {
-  clearSuggestions();
-  getApiObjectHandle().navigateContentWindow(
-      restrictedId, getDispositionFromClickButton(button));
-}
-
-/**
- * chrome.searchBox.onkeypress implementation.
+ * Makes keys navigate through suggestions.
  * @param {Object} e The key being pressed.
  */
 function handleKeyPress(e) {
+  if (!activeBox)
+    return;
+
   switch (e.keyCode) {
-    case 38:  // Up arrow
-      updateSelectedSuggestion(false);
+    case KEY_UP_ARROW:
+      activeBox.selectPrevious();
       break;
-    case 40:  // Down arrow
-      updateSelectedSuggestion(true);
+    case KEY_DOWN_ARROW:
+      activeBox.selectNext();
       break;
   }
 }
 
 /**
- * Handles the postMessage calls from the result iframes.
- * @param {Object} message The message containing details of clicks the iframes.
+ * Handles postMessage calls from suggestion iframes.
+ * @param {Object} message A notification that all iframes are done loading or
+ *     that an iframe was clicked.
  */
 function handleMessage(message) {
-  if (message.origin != 'null' || !message.data ||
-      message.data.eventType != 'click') {
+  if (message.origin != SUGGESTION_ORIGIN)
     return;
-  }
 
-  var iframes = document.getElementsByClassName('contents');
-  for (var i = 0; i < iframes.length; ++i) {
-    if (iframes[i].contentWindow == message.source) {
-      handleSuggestionClick(parseInt(iframes[i].id, 10),
-                            message.data.button);
-      break;
+  if ('loaded' in message.data) {
+    if (pendingBox && pendingBox.isResponseCurrent(message.data.loaded))
+      makePendingSuggestionsActive();
+  } else if ('click' in message.data) {
+    if (activeBox) {
+      var restrictedId = activeBox.getClickTarget(message.source);
+      if (restrictedId != null) {
+        hideActiveSuggestions();
+        getApiObjectHandle().navigateContentWindow(restrictedId,
+            getDispositionFromClickButton(message.data.click));
+      }
     }
   }
 }
 
 /**
- * chrome.searchBox.embeddedSearch.onsubmit implementation.
+ * Sets up the embedded search API and creates suggestion iframes.
  */
-function onSubmit() {
-}
-
-/**
- * Sets up the searchBox API.
- */
-function setUpApi() {
+function init() {
+  iframePool = new IframePool();
+  iframePool.init();
   var apiHandle = getApiObjectHandle();
   apiHandle.onnativesuggestions = updateSuggestions;
   apiHandle.onchange = updateSuggestions;
   apiHandle.onkeypress = handleKeyPress;
-  apiHandle.onsubmit = onSubmit;
-  $('suggestions-box-container').dir = apiHandle.rtl ? 'rtl' : 'ltr';
+  // Instant checks for this handler to be bound.
+  apiHandle.onsubmit = function() {};
+  $qs('.active-container').dir = apiHandle.rtl ? 'rtl' : 'ltr';
+  $qs('.pending-container').dir = apiHandle.rtl ? 'rtl' : 'ltr';
   // Delay adding these styles until the window width is available.
   window.addEventListener('resize', appendSuggestionStyles);
   if (apiHandle.nativeSuggestions.length)
-    handleNativeSuggestions();
+    updateSuggestions();
 }
 
-document.addEventListener('DOMContentLoaded', setUpApi);
+document.addEventListener('DOMContentLoaded', init);
 window.addEventListener('message', handleMessage, false);
+window.addEventListener('blur', function() {
+  if (activeBox)
+    activeBox.clearHover();
+}, false);
+})();