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.
-// ==========================================================
-
 /**
  * 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.
+ * The displayed suggestions.
+ * @type {SuggestionsBox}
+ */
+var active;
+
+/**
+ * The suggestions being rendered.
+ * @type {SuggestionsBox}
+ */
+var pending;
+
+/**
+ * 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} matching selector.
  */
-function $(id) {
-  return document.getElementById(id);
+function $$(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) {
-    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');
+  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() {
+  /**
+   * HTML iframe elements.
+   * @type {Array.<Element>}
+   * @private
+   */
+  this.iframes_ = [];
+}
+
+/**
+ * Initializes the pool with blank result template iframes, positioned off
+ * screen.
+ */
+IframePool.prototype.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 (active)
+        active.hover(e.currentTarget.id);
+    }, false);
+    iframe.addEventListener('mouseout', function(e) {
+      if (active)
+        active.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.
+ */
+IframePool.prototype.reserve = function() {
+  return this.iframes_.pop();
+};
+
+/**
+ * Releases a suggestion iframe back into the pool.
+ * @param {Element} iframe The iframe to return to the pool.
+ */
+IframePool.prototype.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) {
+  /**
+   * Autocomplete fields for this suggestion.
+   * @type {!Object}
+   * @private
+   */
+  this.data_ = data;
+}
+
+/**
+ * Releases the iframe reserved for this suggestion.
+ */
+Suggestion.prototype.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.
+ */
+Suggestion.prototype.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;

[samarth, 2013/04/05 22:30:25]

If we are using closure style, then add this member to the constructor.

[Jered, 2013/04/06 02:45:16]

Not using closure style.

+};
+
+/**
+ * Sets the iframe element for this suggestion.
+ * @param {Element} iframe The iframe.
+ */
+Suggestion.prototype.setIframe = function(iframe) {
+  this.iframe_ = iframe;
+};
+
+/**
+ * @return {number} The restricted id associated with this suggestion.
+ */
+Suggestion.prototype.getRestrictedId = function() {
+  return this.data_.rid;
+};
+
+/**
+ * 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.
+ */
+Suggestion.prototype.reposition = function(isRtl, startMargin, totalMargin) {
+  // Add in the expected parent offset and the top margin.
+  this.iframe_.style.top = this.div_.offsetTop + 4 + 'px';

[samarth, 2013/04/05 22:30:25]

Can you add named constants for the 4 and 26 below? I would not be surprised if
they depend on the platform.

[Jered, 2013/04/06 02:45:16]

Done.

+  // Call parseInt to enforce that startMargin and totalMargin are really
+  // numbers since we're interpolating CSS.
+  this.iframe_.style[isRtl ? 'right' : 'left'] =
+      parseInt(startMargin, 10) + 'px';

[Dan Beam, 2013/04/06 00:18:12]

what happens when this is NaN?

[Jered, 2013/04/06 02:45:16]

Changed to set this style only if finite.

+  this.iframe_.style.width = '-webkit-calc(100% - ' +
+      (parseInt(totalMargin, 10) + 26) + 'px)';
+};
+
+/**
+ * Updates the suggestion selection state.
+ * @param {boolean} selected True if drawn selected or false if not.
+ */
+Suggestion.prototype.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.
+ */
+Suggestion.prototype.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.
+ */
+Suggestion.prototype.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.
+ */
+Suggestion.prototype.hasIframeId = function(id) {
+  return this.iframe_.id == id;
+};
+
+
+/**
+ * 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_ = $$('.pending-container');
+}
+
+/**
+ * Releases suggestion iframes and ignores any load done message for the
+ * current suggestions.
+ */
+SuggestionsBox.prototype.destroy = function() {
+  for (var i = 0, suggestion; suggestion = this.suggestions_[i]; i++) {
+    suggestion.destroy();
+  }

[Dan Beam, 2013/04/06 00:18:12]

doesn't this leave you with a bunch of destroyed suggestions?  why not:

  while (this.suggestions_.length > 0) {
    this.suggestions_.pop().destroy();
  }

[Jered, 2013/04/06 02:45:16]

Done.

+  this.responseId = -1;
+};
+
+/**
+ * Starts rendering new suggestions.
+ */
+SuggestionsBox.prototype.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, suggestion; suggestion = this.suggestions_[i]; i++) {
+    suggestion.appendToBox(box, i == this.selectedIndex_);
+    var iframe = iframePool.reserve();
+    suggestion.setIframe(iframe);
+    iframesToLoad[iframe.id] = suggestion.getRestrictedId();
+  }
+  // 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
+    }
+  };
+  $$('#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.
+ */
+SuggestionsBox.prototype.isResponseCurrent = function(responseId) {
+  return responseId == this.requestId_;
+};
+
+/**
+ * Moves suggestion iframes into position.
+ */
+SuggestionsBox.prototype.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, suggestion; suggestion = this.suggestions_[i]; i++) {
+    suggestion.reposition(isRtl, startMargin, totalMargin);
+  }
+};
+
+/**
+ * Selects the suggestion before the current selection.
+ */
+SuggestionsBox.prototype.selectPrevious = function() {
+  this.changeSelection_(this.selectedIndex_ - 1);
+};
+
+/**
+ * Selects the suggestion after the current selection.
+ */
+SuggestionsBox.prototype.selectNext = function() {
+  this.changeSelection_(this.selectedIndex_ + 1);
+};
+
+/**
+ * Changes the current selected suggestion index.
+ * @param {number} index The new selection to suggest.
+ * @private
+ */
+SuggestionsBox.prototype.changeSelection_ = function(index) {
+  if (index < -1)
+    index = -1;

[Dan Beam, 2013/04/06 00:18:12]

index = Math.min(numSuggestions - 1, Math.max(-1, index));

[Jered, 2013/04/06 02:45:16]

Done.

+  var numSuggestions = this.suggestions_.length;
+  if (index > numSuggestions - 1)
+    index = numSuggestions - 1;
+  this.selectedIndex_ = index;
+
+  this.redrawSelection_();
+  this.redrawHover_();
+};
+
+/**
+ * Redraws the selected suggestion.
+ * @private
+ */
+SuggestionsBox.prototype.redrawSelection_ = function() {
+  var oldSelection = this.container_.querySelector('.selected');

[samarth, 2013/04/05 22:30:25]

Optional: you could have looked up the existing selected suggestion object with
selectedIndex_ and called select(false) on it to be consistent.

[Jered, 2013/04/06 02:45:16]

I like this way because I can tell for sure there'll only be one thing selected,
even if there's some bug with selectedIndex_.

   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);
+  if (this.selectedIndex_ == -1) {
+    this.apiHandle_.setValue(this.inputValue_);
   } else {
-    var newSelection = $('suggestionsBox').querySelector(
-        '.suggestion:nth-of-type(' + (selectedIndex + 1) + ')');
-    newSelection.classList.add('selected');
-    apiHandle.setRestrictedValue(restrictedIds[selectedIndex]);
-  }
-}
-
-// =============================================================================
-//                             Handlers / API stuff
-// =============================================================================
+    this.suggestions_[this.selectedIndex_].select(true);
+    this.apiHandle_.setRestrictedValue(
+        this.suggestions_[this.selectedIndex_].getRestrictedId());
+  }
+};
+
+/**
+ * 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.
+ */
+SuggestionsBox.prototype.getClickTarget = function(iframeWindow) {
+  for (var i = 0, suggestion; suggestion = this.suggestions_[i]; ++i) {
+    if (suggestion.hasIframeWindow(iframeWindow))
+      return suggestion.getRestrictedId();
+  }
+  return null;
+};
+
+/**
+ * Called when the user hovers on the specified iframe.
+ * @param {string} iframeId The id of the iframe hovered.
+ */
+SuggestionsBox.prototype.hover = function(iframeId) {
+  this.hoveredIndex_ = -1;
+  for (var i = 0, suggestion; suggestion = this.suggestions_[i]; ++i) {
+    if (suggestion.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.
+ */
+SuggestionsBox.prototype.unhover = function(iframeId) {
+  if (this.suggestions_[this.hoveredIndex_] &&
+      this.suggestions_[this.hoveredIndex_].hasIframeId(iframeId)) {
+    this.clearHover();
+  }
+};
+
+/**
+ * Clears the current hover.
+ */
+SuggestionsBox.prototype.clearHover = function() {
+  this.hoveredIndex_ = -1;
+  this.redrawHover_();
+};
+
+/**
+ * Redraws the mouse hover background.
+ * @private
+ */
+SuggestionsBox.prototype.redrawHover_ = function() {
+  var oldHover = this.container_.querySelector('.hovered');
+  if (oldHover)
+    oldHover.classList.remove('hovered');

[samarth, 2013/04/05 22:30:25]

Again, it's weird that you have a .hover() method on the suggestion but then
sometimes explicitly change the class here. But I don't care all that much if
it's a lot of work to change this.

[Jered, 2013/04/06 02:45:16]

See above. It's mostly paranoia from past uis that had bugs with multiple
selections.

+  if (this.hoveredIndex_ != -1 && this.hoveredIndex_ != this.selectedIndex_)
+    this.suggestions_[this.hoveredIndex_].hover(true);
+};
+
+/**
+ * Marks the suggestions container as active.
+ */
+SuggestionsBox.prototype.activate = function() {
+  this.container_.className = 'active-container';
+};
+
+/**
+ * Marks the suggestions container as inactive.
+ */
+SuggestionsBox.prototype.deactivate = function() {
+  this.container_.className = 'pending-container';
+  this.container_.innerHTML = '';
+};
+
+/**
+ * @return {number} The height of the suggestions container.
+ */
+SuggestionsBox.prototype.getHeight = function() {
+  return this.container_.offsetHeight;
+};
+
+/**
+ * Clears the currently active suggestions and shows pending suggestions.
+ */
+function makePendingSuggestionsActive() {
+  if (active) {

[samarth, 2013/04/05 22:30:25]

Yay, I can understand this function now :)

[Jered, 2013/04/06 02:45:16]

Awesome!

+    active.deactivate();
+    active.destroy();
+  } else {
+    // Initially there will be no active suggestions, but we still want to use
+    // div.active-container to load the next suggestions.
+    $$('.active-container').className = 'pending-container';
+  }
+  pending.activate();
+  active = pending;
+  pending = null;
+  active.repositionSuggestions();
+  getApiObjectHandle().showOverlay(active.getHeight());
+}
+
+/**
+ * Hides the active suggestions box.
+ */
+function hideActiveSuggestions() {
+  getApiObjectHandle().showOverlay(0);
+  if (active) {
+    $$('.active-container').innerHTML = '';
+    active.destroy();
+  }
+  active = 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 (pending) {
+    pending.destroy();
+    pending = null;
+  }
   var apiHandle = getApiObjectHandle();
-  lastInputValue = apiHandle.value;
-
-  clearSuggestions();
-  var nativeSuggestions = apiHandle.nativeSuggestions;
-  if (nativeSuggestions.length) {
-    nativeSuggestions.sort(function(a, b) {
+  var inputValue = apiHandle.value;
+  var suggestions = apiHandle.nativeSuggestions;
+  if (!inputValue || !suggestions.length) {
+    hideActiveSuggestions();
+    return;
+  }
+  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))

[samarth, 2013/04/05 22:30:25]

Optional: you can make this a method on the Suggestion object, so
if (suggestions[0].shouldSelect(apiHandle.verbatim)) {
}

[Jered, 2013/04/06 02:45:16]

Alas, this is suggestionData, not a Suggestion object.

       selectedIndex = 0;
-    renderSuggestions(nativeSuggestions);
+    pending = new SuggestionsBox(inputValue,
+        suggestions.slice(0, MAX_SUGGESTIONS_TO_SHOW), selectedIndex);
+    pending.loadSuggestions();
   }
-
-  var height = getDropdownHeight();
-  apiHandle.showOverlay(height);
 }
 
 /**
  * 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);
+  $$('head').appendChild(style);
+  if (active)
+    active.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 (!active)
+    return;

[Dan Beam, 2013/04/06 00:18:12]

nit: \n

[Jered, 2013/04/06 02:45:16]

Done.

   switch (e.keyCode) {
-    case 38:  // Up arrow
-      updateSelectedSuggestion(false);
+    case KEY_UP_ARROW:
+      active.selectPrevious();
       break;
-    case 40:  // Down arrow
-      updateSelectedSuggestion(true);
+    case KEY_DOWN_ARROW:
+      active.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 (pending && pending.isResponseCurrent(message.data.loaded)) {
+      makePendingSuggestionsActive();
+    }
+  } else if ('click' in message.data) {
+    if (active) {
+      var restrictedId = active.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() {};
+  $$('.active-container').dir = apiHandle.rtl ? 'rtl' : 'ltr';
+  $$('.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 (active)
+    active.clearHover();
+}, false);