browser/components/urlbar/UrlbarView.jsm
author Marco Bonardo <mbonardo@mozilla.com>
Wed, 08 May 2019 21:14:35 +0000
changeset 535013 d6756af108596e5a27548d397f1dd72d44c45854
parent 535012 876559fca157d87c6b39f57ee4995dc09fff0db2
child 535118 1e371ad57bd0be4039954e30bc0832350e9f3656
permissions -rw-r--r--
Bug 1535656 - Quantum bar results flicker while typing a search. r=dao Differential Revision: https://phabricator.services.mozilla.com/D30190

/* This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */

"use strict";

var EXPORTED_SYMBOLS = ["UrlbarView"];

const {XPCOMUtils} = ChromeUtils.import("resource://gre/modules/XPCOMUtils.jsm");
XPCOMUtils.defineLazyModuleGetters(this, {
  Services: "resource://gre/modules/Services.jsm",
  UrlbarPrefs: "resource:///modules/UrlbarPrefs.jsm",
  UrlbarTokenizer: "resource:///modules/UrlbarTokenizer.jsm",
  UrlbarUtils: "resource:///modules/UrlbarUtils.jsm",
  AppConstants: "resource://gre/modules/AppConstants.jsm",
});

XPCOMUtils.defineLazyGetter(this, "bundle", function() {
  return Services.strings.createBundle("chrome://global/locale/autocomplete.properties");
});

/**
 * Receives and displays address bar autocomplete results.
 */
class UrlbarView {
  /**
   * @param {UrlbarInput} input
   *   The UrlbarInput instance belonging to this UrlbarView instance.
   */
  constructor(input) {
    this.input = input;
    this.panel = input.panel;
    this.controller = input.controller;
    this.document = this.panel.ownerDocument;
    this.window = this.document.defaultView;

    this._mainContainer = this.panel.querySelector(".urlbarView-body-inner");
    this._rows = this.panel.querySelector("#urlbarView-results");

    this._rows.addEventListener("mousedown", this);
    this._rows.addEventListener("mouseup", this);

    // For the horizontal fade-out effect, set the overflow attribute on result
    // rows when they overflow.
    this._rows.addEventListener("overflow", this);
    this._rows.addEventListener("underflow", this);

    this.panel.addEventListener("popupshowing", this);
    this.panel.addEventListener("popupshown", this);
    this.panel.addEventListener("popuphiding", this);

    this.controller.setView(this);
    this.controller.addQueryListener(this);
  }

  get oneOffSearchButtons() {
    if (!this._oneOffSearchButtons) {
      this._oneOffSearchButtons =
        new this.window.SearchOneOffs(this.panel.querySelector(".search-one-offs"));
      this._oneOffSearchButtons.addEventListener("SelectedOneOffButtonChanged", this);
    }
    return this._oneOffSearchButtons;
  }

  /**
   * @returns {boolean}
   *   Whether the panel is open.
   */
  get isOpen() {
    return this.panel.state == "open" || this.panel.state == "showing";
  }

  get allowEmptySelection() {
    return !(this._queryContext &&
             this._queryContext.results[0] &&
             this._queryContext.results[0].heuristic);
  }

  get selectedIndex() {
    if (!this.isOpen || !this._selected) {
      return -1;
    }
    return parseInt(this._selected.getAttribute("resultIndex"));
  }

  set selectedIndex(val) {
    if (!this.isOpen) {
      throw new Error("UrlbarView: Cannot select an item if the view isn't open.");
    }

    if (val < 0) {
      this._selectItem(null);
      return val;
    }

    let items = Array.from(this._rows.children)
                     .filter(r => r.style.display != "none");
    if (val >= items.length) {
      throw new Error(`UrlbarView: Index ${val} is out of bounds.`);
    }
    this._selectItem(items[val]);
    return val;
  }

  /**
   * @returns {UrlbarResult}
   *   The currently selected result.
   */
  get selectedResult() {
    if (!this.isOpen || !this._selected) {
      return null;
    }
    return this._selected.result;
  }

  /**
   * Gets the result for the index.
   * @param {number} index
   *   The index to look up.
   * @returns {UrlbarResult}
   */
  getResult(index) {
    if (index < 0 || index > this._queryContext.results.length) {
      throw new Error(`UrlbarView: Index ${index} is out of bounds`);
    }
    return this._queryContext.results[index];
  }

  /**
   * Moves the view selection forward or backward.
   *
   * @param {number} amount
   *   The number of steps to move.
   * @param {boolean} options.reverse
   *   Set to true to select the previous item. By default the next item
   *   will be selected.
   */
  selectBy(amount, {reverse = false} = {}) {
    if (!this.isOpen) {
      throw new Error("UrlbarView: Cannot select an item if the view isn't open.");
    }

    // Freeze results as the user is interacting with them.
    this.controller.cancelQuery();

    let row = this._selected;

    // Results over maxResults may be hidden and should not be selectable.
    let lastElementChild = this._rows.lastElementChild;
    while (lastElementChild && lastElementChild.style.display == "none") {
      lastElementChild = lastElementChild.previousElementSibling;
    }

    if (!row) {
      this._selectItem(reverse ? lastElementChild :
                                 this._rows.firstElementChild);
      return;
    }

    let endReached = reverse ?
      (row == this._rows.firstElementChild) :
      (row == lastElementChild);
    if (endReached) {
      if (this.allowEmptySelection) {
        row = null;
      } else {
        row = reverse ? lastElementChild :
                        this._rows.firstElementChild;
      }
      this._selectItem(row);
      return;
    }

    while (amount-- > 0) {
      let next = reverse ? row.previousElementSibling : row.nextElementSibling;
      if (!next) {
        break;
      }
      if (next.style.display == "none") {
        continue;
      }
      row = next;
    }
    this._selectItem(row);
  }

  removeAccessibleFocus() {
    this._setAccessibleFocus(null);
  }

  /**
   * Closes the autocomplete popup, cancelling the query if necessary.
   */
  close() {
    this.controller.cancelQuery();
    this.panel.hidePopup();
  }

  // UrlbarController listener methods.
  onQueryStarted(queryContext) {
    this._queryWasCancelled = false;
    this._startRemoveStaleRowsTimer();
  }

  onQueryCancelled(queryContext) {
    this._queryWasCancelled = true;
    this._cancelRemoveStaleRowsTimer();
  }

  onQueryFinished(queryContext) {
    this._cancelRemoveStaleRowsTimer();
    // If the query has not been canceled, remove stale rows immediately.
    if (!this._queryWasCancelled) {
      this._removeStaleRows();
    }
  }

  onQueryResults(queryContext) {
    this._queryContext = queryContext;

    this._updateResults(queryContext);

    let isFirstPreselectedResult = false;
    if (queryContext.lastResultCount == 0) {
      if (queryContext.preselected) {
        isFirstPreselectedResult = true;
        this._selectItem(this._rows.firstElementChild, {
          updateInput: false,
          setAccessibleFocus: this.controller._userSelectionBehavior == "arrow",
        });
      } else {
        // Clear the selection when we get a new set of results.
        this._selectItem(null);
      }
      // Hide the one-off search buttons if the input starts with a potential @
      // search alias or the search restriction character.
      let trimmedValue = this.input.textValue.trim();
      this._enableOrDisableOneOffSearches(
        !trimmedValue ||
        (trimmedValue[0] != "@" &&
         (trimmedValue[0] != UrlbarTokenizer.RESTRICT.SEARCH ||
          trimmedValue.length != 1))
      );
    }

    this._openPanel();

    if (isFirstPreselectedResult) {
      // The first, preselected result may be a search alias result, so apply
      // formatting if necessary.  Conversely, the first result of the previous
      // query may have been an alias, so remove formatting if necessary.
      this.input.formatValue();
    }
  }

  /**
   * Handles removing a result from the view when it is removed from the query,
   * and attempts to select the new result on the same row.
   *
   * This assumes that the result rows are in index order.
   *
   * @param {number} index The index of the result that has been removed.
   */
  onQueryResultRemoved(index) {
    // Change the index for any rows above the removed index.
    for (let i = index + 1; i < this._rows.children.length; i++) {
      let child = this._rows.children[i];
      child.setAttribute("resultIndex", child.getAttribute("resultIndex") - 1);
    }

    let rowToRemove = this._rows.children[index];
    rowToRemove.remove();

    if (rowToRemove != this._selected) {
      return;
    }

    // Select the row at the same index, if possible.
    let newSelectionIndex = index;
    if (index >= this._queryContext.results.length) {
      newSelectionIndex = this._queryContext.results.length - 1;
    }
    if (newSelectionIndex >= 0) {
      this.selectedIndex = newSelectionIndex;
    }
  }

  /**
   * Notified when the view context changes, for example when switching tabs.
   * It can be used to reset internal state tracking.
   */
  onViewContextChanged() {
    // Clear rows, so that when reusing results we don't visually leak them
    // across different contexts.
    this._rows.textContent = "";
  }

  /**
   * Passes DOM events for the view to the _on_<event type> methods.
   * @param {Event} event
   *   DOM event from the <view>.
   */
  handleEvent(event) {
    let methodName = "_on_" + event.type;
    if (methodName in this) {
      this[methodName](event);
    } else {
      throw new Error("Unrecognized UrlbarView event: " + event.type);
    }
  }

  /**
   * This is called when a one-off is clicked and when "search in new tab"
   * is selected from a one-off context menu.
   * @param {Event} event
   * @param {nsISearchEngine} engine
   * @param {string} where
   * @param {object} params
   */
  handleOneOffSearch(event, engine, where, params) {
    this.input.handleCommand(event, where, params);
  }

  // Private methods below.

  _getBoundsWithoutFlushing(element) {
    return this.window.windowUtils.getBoundsWithoutFlushing(element);
  }

  _createElement(name) {
    return this.document.createElementNS("http://www.w3.org/1999/xhtml", name);
  }

  _openPanel() {
    if (this.isOpen) {
      return;
    }
    this.controller.userSelectionBehavior = "none";

    this.panel.removeAttribute("hidden");
    this.panel.removeAttribute("actionoverride");

    // Make the panel span the width of the window.
    let px = number => number.toFixed(2) + "px";
    let documentRect =
      this._getBoundsWithoutFlushing(this.document.documentElement);
    let width = documentRect.right - documentRect.left;
    this.panel.setAttribute("width", width);
    this._mainContainer.style.maxWidth = px(width);

    // Keep the popup items' site icons aligned with the input's identity
    // icon if it's not too far from the edge of the window.  We define
    // "too far" as "more than 30% of the window's width AND more than
    // 250px".
    let boundToCheck = this.window.RTL_UI ? "right" : "left";
    let inputRect = this._getBoundsWithoutFlushing(this.input.textbox);
    let startOffset = Math.abs(inputRect[boundToCheck] - documentRect[boundToCheck]);
    let alignSiteIcons = startOffset / width <= 0.3 || startOffset <= 250;
    if (alignSiteIcons) {
      // Calculate the end margin if we have a start margin.
      let boundToCheckEnd = this.window.RTL_UI ? "left" : "right";
      let endOffset = Math.abs(inputRect[boundToCheckEnd] -
                               documentRect[boundToCheckEnd]);
      if (endOffset > startOffset * 2) {
        // Provide more space when aligning would result in an unbalanced
        // margin. This allows the location bar to be moved to the start
        // of the navigation toolbar to reclaim space for results.
        endOffset = startOffset;
      }
      let identityIcon = this.document.getElementById("identity-icon");
      let identityRect = this._getBoundsWithoutFlushing(identityIcon);
      let start = this.window.RTL_UI ?
                    documentRect.right - identityRect.right :
                    identityRect.left;

      this.panel.style.setProperty("--item-padding-start", px(start));
      this.panel.style.setProperty("--item-padding-end", px(endOffset));
    } else {
      this.panel.style.removeProperty("--item-padding-start");
      this.panel.style.removeProperty("--item-padding-end");
    }

    // Align the panel with the input's parent toolbar.
    let toolbarRect =
      this._getBoundsWithoutFlushing(this.input.textbox.closest("toolbar"));
    let horizontalOffset = this.window.RTL_UI ?
      inputRect.right - documentRect.right :
      documentRect.left - inputRect.left;
    let verticalOffset = inputRect.top - toolbarRect.top;
    if (AppConstants.platform == "macosx") {
      // Adjust vertical offset to account for the popup's native outer border.
      verticalOffset++;
    }
    this.panel.style.marginInlineStart = px(horizontalOffset);
    this.panel.style.marginTop = px(verticalOffset);

    this.panel.openPopup(this.input.textbox, "after_start");
  }

  /**
   * Whether a result is a search suggestion.
   * @param {UrlbarResult} result The result to examine.
   * @returns {boolean} Whether the result is a search suggestion.
   */
  _resultIsSearchSuggestion(result) {
    return Boolean(result &&
                   result.type == UrlbarUtils.RESULT_TYPE.SEARCH &&
                   result.payload.suggestion);
  }

  /**
   * Checks whether the given row index can be update to the result we want
   * to apply. This is used in _updateResults to avoid flickering of results, by
   * reusing existing rows.
   * @param {number} rowIndex Index of the row to examine.
   * @param {UrlbarResult} result The result we'd like to apply.
   * @param {number} firstSearchSuggestionIndex Index of the first search suggestion.
   * @param {number} lastSearchSuggestionIndex Index of the last search suggestion.
   * @returns {boolean} Whether the row can be updated to this result.
   */
  _rowCanUpdateToResult(rowIndex, result, firstSearchSuggestionIndex,
                        lastSearchSuggestionIndex) {
    // The heuristic result must always be current, thus it's always compatible.
    if (result.heuristic) {
      return true;
    }
    let row = this._rows.children[rowIndex];
    let resultIsSearchSuggestion = this._resultIsSearchSuggestion(result);
    // If the row is same type, just update it.
    if (resultIsSearchSuggestion == this._resultIsSearchSuggestion(row.result)) {
      return true;
    }
    // If the row has a different type, update it if we are in a compatible
    // index range.
    // In practice we don't want to overwrite a search suggestion with a non
    // search suggestion, but we allow the opposite.
    return resultIsSearchSuggestion && rowIndex >= firstSearchSuggestionIndex;
  }

  _updateResults(queryContext) {
    // TODO: For now this just compares search suggestions to the rest, in the
    // future we should make it support any type of result. Or, even better,
    // results should be grouped, thus we can directly update groups.

    // Find where are existing search suggestions.
    let firstSearchSuggestionIndex = -1;
    let lastSearchSuggestionIndex = -1;
    for (let i = 0; i < this._rows.children.length; ++i) {
      let row = this._rows.children[i];
      // Mark every row as stale, _updateRow will unmark them later.
      row.setAttribute("stale", "true");
      // Skip any row that isn't a search suggestion, or is non-visible because
      // over maxResults.
      if (row.result.heuristic ||
          i >= queryContext.maxResults ||
          !this._resultIsSearchSuggestion(row.result)) {
        continue;
      }
      if (firstSearchSuggestionIndex == -1) {
        firstSearchSuggestionIndex = i;
      }
      lastSearchSuggestionIndex = i;
    }

    // Walk rows and find an insertion index for results. To avoid flicker, we
    // skip rows until we find one compatible with the result we want to apply.
    // If we couldn't find a compatible range, we'll just update.
    let results = queryContext.results;
    let resultIndex = 0;
    // We can have more rows than the visible ones.
    for (let rowIndex = 0;
         rowIndex < this._rows.children.length && resultIndex < results.length;
         ++rowIndex) {
      let row = this._rows.children[rowIndex];
      let result = results[resultIndex];
      if (this._rowCanUpdateToResult(rowIndex, result,
                                     firstSearchSuggestionIndex,
                                     lastSearchSuggestionIndex)) {
        this._updateRow(row, result);
        resultIndex++;
      }
    }
    // Add remaining results, if we have fewer rows than results.
    for (; resultIndex < results.length; ++resultIndex) {
      let row = this._createRow();
      this._updateRow(row, results[resultIndex]);
      // Due to stale rows, we may have more rows than maxResults, thus we must
      // hide them, and we'll revert this when stale rows are removed.
      if (this._rows.children.length >= queryContext.maxResults) {
        row.style.display = "none";
      }
      this._rows.appendChild(row);
    }
  }

  _createRow() {
    let item = this._createElement("div");
    item.className = "urlbarView-row";
    item.setAttribute("role", "option");
    item._elements = new Map;

    let content = this._createElement("span");
    content.className = "urlbarView-row-inner";
    item.appendChild(content);

    let typeIcon = this._createElement("span");
    typeIcon.className = "urlbarView-type-icon";
    content.appendChild(typeIcon);

    let favicon = this._createElement("img");
    favicon.className = "urlbarView-favicon";
    content.appendChild(favicon);
    item._elements.set("favicon", favicon);

    let title = this._createElement("span");
    title.className = "urlbarView-title";
    content.appendChild(title);
    item._elements.set("title", title);

    let tagsContainer = this._createElement("span");
    tagsContainer.className = "urlbarView-tags";
    content.appendChild(tagsContainer);
    item._elements.set("tagsContainer", tagsContainer);

    let titleSeparator = this._createElement("span");
    titleSeparator.className = "urlbarView-title-separator";
    content.appendChild(titleSeparator);
    item._elements.set("titleSeparator", titleSeparator);

    let action = this._createElement("span");
    action.className = "urlbarView-secondary urlbarView-action";
    content.appendChild(action);
    item._elements.set("action", action);

    let url = this._createElement("span");
    url.className = "urlbarView-secondary urlbarView-url";
    content.appendChild(url);
    item._elements.set("url", url);

    return item;
  }

  _updateRow(item, result) {
    let resultIndex = this._queryContext.results.indexOf(result);
    item.result = result;
    item.removeAttribute("stale");
    item.id = "urlbarView-row-" + resultIndex;
    item.setAttribute("resultIndex", resultIndex);

    if (result.type == UrlbarUtils.RESULT_TYPE.SEARCH &&
        !result.payload.isKeywordOffer) {
      item.setAttribute("type", "search");
    } else if (result.type == UrlbarUtils.RESULT_TYPE.REMOTE_TAB) {
      item.setAttribute("type", "remotetab");
    } else if (result.type == UrlbarUtils.RESULT_TYPE.TAB_SWITCH) {
      item.setAttribute("type", "switchtab");
    } else if (result.source == UrlbarUtils.RESULT_SOURCE.BOOKMARKS) {
      item.setAttribute("type", "bookmark");
    } else {
      item.removeAttribute("type");
    }

    let favicon = item._elements.get("favicon");
    if (result.type == UrlbarUtils.RESULT_TYPE.SEARCH ||
        result.type == UrlbarUtils.RESULT_TYPE.KEYWORD) {
      favicon.src = result.payload.icon || UrlbarUtils.ICON.SEARCH_GLASS;
    } else {
      favicon.src = result.payload.icon || UrlbarUtils.ICON.DEFAULT;
    }

    let title = item._elements.get("title");
    this._addTextContentWithHighlights(
      title, result.title, result.titleHighlights);

    let tagsContainer = item._elements.get("tagsContainer");
    tagsContainer.textContent = "";
    if (result.payload.tags && result.payload.tags.length > 0) {
      tagsContainer.append(...result.payload.tags.map((tag, i) => {
        const element = this._createElement("span");
        element.className = "urlbarView-tag";
        this._addTextContentWithHighlights(
          element, tag, result.payloadHighlights.tags[i]);
        return element;
      }));
    }

    let action = "";
    let isVisitAction = false;
    let setURL = false;
    switch (result.type) {
      case UrlbarUtils.RESULT_TYPE.TAB_SWITCH:
        action = bundle.GetStringFromName("switchToTab2");
        setURL = true;
        break;
      case UrlbarUtils.RESULT_TYPE.REMOTE_TAB:
        action = result.payload.device;
        setURL = true;
        break;
      case UrlbarUtils.RESULT_TYPE.SEARCH:
        action = bundle.formatStringFromName("searchWithEngine",
                                             [result.payload.engine], 1);
        break;
      case UrlbarUtils.RESULT_TYPE.KEYWORD:
        isVisitAction = result.payload.input.trim() == result.payload.keyword;
        break;
      case UrlbarUtils.RESULT_TYPE.OMNIBOX:
        action = result.payload.content;
        break;
      default:
        if (result.heuristic) {
          isVisitAction = true;
        } else {
          setURL = true;
        }
        break;
    }

    let url = item._elements.get("url");
    if (setURL) {
      this._addTextContentWithHighlights(url, result.payload.displayUrl,
                                         result.payloadHighlights.displayUrl || []);
    } else {
      url.textContent = "";
    }

    if (isVisitAction) {
      action = bundle.GetStringFromName("visit");
      title.setAttribute("isurl", "true");
    } else {
      title.removeAttribute("isurl");
    }
    item._elements.get("action").textContent = action;

    item._elements.get("titleSeparator").hidden = !action && !setURL;
  }

  _removeStaleRows() {
    let row = this._rows.lastElementChild;
    while (row) {
      let next = row.previousElementSibling;
      if (row.hasAttribute("stale")) {
        row.remove();
      } else {
        row.style.display = "";
      }
      row = next;
    }
  }

  _startRemoveStaleRowsTimer() {
    this._removeStaleRowsTimer = this.window.setTimeout(() => {
      this._removeStaleRowsTimer = null;
      this._removeStaleRows();
    }, 200);
  }

  _cancelRemoveStaleRowsTimer() {
    if (this._removeStaleRowsTimer) {
      this.window.clearTimeout(this._removeStaleRowsTimer);
      this._removeStaleRowsTimer = null;
    }
  }

  _selectItem(item, {
    updateInput = true,
    setAccessibleFocus = true,
  } = {}) {
    if (this._selected) {
      this._selected.toggleAttribute("selected", false);
      this._selected.removeAttribute("aria-selected");
    }
    if (item) {
      item.toggleAttribute("selected", true);
      item.setAttribute("aria-selected", "true");
    }
    this._setAccessibleFocus(setAccessibleFocus && item);
    this._selected = item;

    if (updateInput) {
      this.input.setValueFromResult(item && item.result);
    }
  }

  _setAccessibleFocus(item) {
    if (item) {
      this.input.inputField.setAttribute("aria-activedescendant", item.id);
    } else {
      this.input.inputField.removeAttribute("aria-activedescendant");
    }
  }

  /**
   * Adds text content to a node, placing substrings that should be highlighted
   * inside <em> nodes.
   *
   * @param {Node} parentNode
   *   The text content will be added to this node.
   * @param {string} textContent
   *   The text content to give the node.
   * @param {array} highlights
   *   The matches to highlight in the text.
   */
  _addTextContentWithHighlights(parentNode, textContent, highlights) {
    parentNode.textContent = "";
    if (!textContent) {
      return;
    }
    highlights = (highlights || []).concat([[textContent.length, 0]]);
    let index = 0;
    for (let [highlightIndex, highlightLength] of highlights) {
      if (highlightIndex - index > 0) {
        parentNode.appendChild(
          this.document.createTextNode(
            textContent.substring(index, highlightIndex)
          )
        );
      }
      if (highlightLength > 0) {
        let strong = this._createElement("strong");
        strong.textContent = textContent.substring(
          highlightIndex,
          highlightIndex + highlightLength
        );
        parentNode.appendChild(strong);
      }
      index = highlightIndex + highlightLength;
    }
  }

  _enableOrDisableOneOffSearches(enable = true) {
    if (enable && UrlbarPrefs.get("oneOffSearches")) {
      this.oneOffSearchButtons.telemetryOrigin = "urlbar";
      this.oneOffSearchButtons.style.display = "";
      // Set .textbox first, since the popup setter will cause
      // a _rebuild call that uses it.
      this.oneOffSearchButtons.textbox = this.input.textbox;
      this.oneOffSearchButtons.view = this;
    } else {
      this.oneOffSearchButtons.telemetryOrigin = null;
      this.oneOffSearchButtons.style.display = "none";
      this.oneOffSearchButtons.textbox = null;
      this.oneOffSearchButtons.view = null;
    }
  }

  _on_SelectedOneOffButtonChanged() {
    if (!this.isOpen || !this._queryContext) {
      return;
    }

    // Update all search suggestion results to use the newly selected engine, or
    // if no engine is selected, revert to their original engines.
    let engine =
      this.oneOffSearchButtons.selectedButton &&
      this.oneOffSearchButtons.selectedButton.engine;
    for (let i = 0; i < this._queryContext.results.length; i++) {
      let result = this._queryContext.results[i];
      if (result.type != UrlbarUtils.RESULT_TYPE.SEARCH ||
          (!result.heuristic && !result.payload.suggestion)) {
        continue;
      }
      if (engine) {
        if (!result.payload.originalEngine) {
          result.payload.originalEngine = result.payload.engine;
        }
        result.payload.engine = engine.name;
      } else if (result.payload.originalEngine) {
        result.payload.engine = result.payload.originalEngine;
        delete result.payload.originalEngine;
      }
      let item = this._rows.children[i];
      let action = item.querySelector(".urlbarView-action");
      action.textContent =
        bundle.formatStringFromName("searchWithEngine",
          [(engine && engine.name) || result.payload.engine], 1);
      // If we just changed the engine from the original engine and it had an
      // icon, then make sure the result now uses the new engine's icon or
      // failing that the default icon.  If we changed it back to the original
      // engine, go back to the original or default icon.
      let favicon = item.querySelector(".urlbarView-favicon");
      if (engine && result.payload.icon) {
        favicon.src =
          (engine.iconURI && engine.iconURI.spec) ||
          UrlbarUtils.ICON.SEARCH_GLASS;
      } else if (!engine) {
        favicon.src = result.payload.icon || UrlbarUtils.ICON.SEARCH_GLASS;
      }
    }
  }

  _on_mousedown(event) {
    if (event.button == 2) {
      // Ignore right clicks.
      return;
    }

    let row = event.target;
    while (!row.classList.contains("urlbarView-row")) {
      row = row.parentNode;
    }
    this._selectItem(row, { updateInput: false });
    this.controller.speculativeConnect(this._queryContext, this.selectedIndex, "mousedown");
  }

  _on_mouseup(event) {
    if (event.button == 2) {
      // Ignore right clicks.
      return;
    }

    let row = event.target;
    while (!row.classList.contains("urlbarView-row")) {
      row = row.parentNode;
    }
    this.input.pickResult(event, parseInt(row.getAttribute("resultIndex")));
  }

  _on_overflow(event) {
    if (event.detail == 1 &&
        (event.target.classList.contains("urlbarView-url") ||
         event.target.classList.contains("urlbarView-title"))) {
      event.target.toggleAttribute("overflow", true);
    }
  }

  _on_underflow(event) {
    if (event.detail == 1 &&
        (event.target.classList.contains("urlbarView-url") ||
         event.target.classList.contains("urlbarView-title"))) {
      event.target.toggleAttribute("overflow", false);
    }
  }

  _on_popupshowing() {
    this.window.addEventListener("resize", this);
  }

  _on_popupshown() {
    this.input.inputField.setAttribute("aria-expanded", "true");
  }

  _on_popuphiding() {
    this.controller.cancelQuery();
    this.window.removeEventListener("resize", this);
    this.removeAccessibleFocus();
    this.input.inputField.setAttribute("aria-expanded", "false");
    this._rows.textContent = "";
  }

  _on_resize() {
    // Close the popup as it would be wrongly sized. This can
    // happen when using special OS resize functions like Win+Arrow.
    this.close();
  }
}