Issue #303 Part 1: Move basilisk files from /browser to /application/basilisk

1 files changed, 0 insertions, 1244 deletions

diff --git a/browser/base/content/browser-gestureSupport.js b/browser/base/content/browser-gestureSupport.js
deleted file mode 100644
index f472e5c9a..000000000
--- a/browser/base/content/browser-gestureSupport.js
+++ /dev/null
@@ -1,1244 +0,0 @@
-/* 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/. */
-
-// Simple gestures support
-//
-// As per bug #412486, web content must not be allowed to receive any
-// simple gesture events.  Multi-touch gesture APIs are in their
-// infancy and we do NOT want to be forced into supporting an API that
-// will probably have to change in the future.  (The current Mac OS X
-// API is undocumented and was reverse-engineered.)  Until support is
-// implemented in the event dispatcher to keep these events as
-// chrome-only, we must listen for the simple gesture events during
-// the capturing phase and call stopPropagation on every event.
-
-var gGestureSupport = {
-  _currentRotation: 0,
-  _lastRotateDelta: 0,
-  _rotateMomentumThreshold: .75,
-
-  /**
-   * Add or remove mouse gesture event listeners
-   *
-   * @param aAddListener
-   *        True to add/init listeners and false to remove/uninit
-   */
-  init: function GS_init(aAddListener) {
-    const gestureEvents = ["SwipeGestureMayStart", "SwipeGestureStart",
-      "SwipeGestureUpdate", "SwipeGestureEnd", "SwipeGesture",
-      "MagnifyGestureStart", "MagnifyGestureUpdate", "MagnifyGesture",
-      "RotateGestureStart", "RotateGestureUpdate", "RotateGesture",
-      "TapGesture", "PressTapGesture"];
-
-    let addRemove = aAddListener ? window.addEventListener :
-      window.removeEventListener;
-
-    for (let event of gestureEvents) {
-      addRemove("Moz" + event, this, true);
-    }
-  },
-
-  /**
-   * Dispatch events based on the type of mouse gesture event. For now, make
-   * sure to stop propagation of every gesture event so that web content cannot
-   * receive gesture events.
-   *
-   * @param aEvent
-   *        The gesture event to handle
-   */
-  handleEvent: function GS_handleEvent(aEvent) {
-    if (!Services.prefs.getBoolPref(
-           "dom.debug.propagate_gesture_events_through_content")) {
-      aEvent.stopPropagation();
-    }
-
-    // Create a preference object with some defaults
-    let def = (aThreshold, aLatched) =>
-      ({ threshold: aThreshold, latched: !!aLatched });
-
-    switch (aEvent.type) {
-      case "MozSwipeGestureMayStart":
-        if (this._shouldDoSwipeGesture(aEvent)) {
-          aEvent.preventDefault();
-        }
-        break;
-      case "MozSwipeGestureStart":
-        aEvent.preventDefault();
-        this._setupSwipeGesture();
-        break;
-      case "MozSwipeGestureUpdate":
-        aEvent.preventDefault();
-        this._doUpdate(aEvent);
-        break;
-      case "MozSwipeGestureEnd":
-        aEvent.preventDefault();
-        this._doEnd(aEvent);
-        break;
-      case "MozSwipeGesture":
-        aEvent.preventDefault();
-        this.onSwipe(aEvent);
-        break;
-      case "MozMagnifyGestureStart":
-        aEvent.preventDefault();
-        let pinchPref = AppConstants.platform == "win"
-                        ? def(25, 0)
-                        : def(150, 1);
-        this._setupGesture(aEvent, "pinch", pinchPref, "out", "in");
-        break;
-      case "MozRotateGestureStart":
-        aEvent.preventDefault();
-        this._setupGesture(aEvent, "twist", def(25, 0), "right", "left");
-        break;
-      case "MozMagnifyGestureUpdate":
-      case "MozRotateGestureUpdate":
-        aEvent.preventDefault();
-        this._doUpdate(aEvent);
-        break;
-      case "MozTapGesture":
-        aEvent.preventDefault();
-        this._doAction(aEvent, ["tap"]);
-        break;
-      case "MozRotateGesture":
-        aEvent.preventDefault();
-        this._doAction(aEvent, ["twist", "end"]);
-        break;
-      /* case "MozPressTapGesture":
-        break; */
-    }
-  },
-
-  /**
-   * Called at the start of "pinch" and "twist" gestures to setup all of the
-   * information needed to process the gesture
-   *
-   * @param aEvent
-   *        The continual motion start event to handle
-   * @param aGesture
-   *        Name of the gesture to handle
-   * @param aPref
-   *        Preference object with the names of preferences and defaults
-   * @param aInc
-   *        Command to trigger for increasing motion (without gesture name)
-   * @param aDec
-   *        Command to trigger for decreasing motion (without gesture name)
-   */
-  _setupGesture: function GS__setupGesture(aEvent, aGesture, aPref, aInc, aDec) {
-    // Try to load user-set values from preferences
-    for (let [pref, def] of Object.entries(aPref))
-      aPref[pref] = this._getPref(aGesture + "." + pref, def);
-
-    // Keep track of the total deltas and latching behavior
-    let offset = 0;
-    let latchDir = aEvent.delta > 0 ? 1 : -1;
-    let isLatched = false;
-
-    // Create the update function here to capture closure state
-    this._doUpdate = function GS__doUpdate(aEvent) {
-      // Update the offset with new event data
-      offset += aEvent.delta;
-
-      // Check if the cumulative deltas exceed the threshold
-      if (Math.abs(offset) > aPref["threshold"]) {
-        // Trigger the action if we don't care about latching; otherwise, make
-        // sure either we're not latched and going the same direction of the
-        // initial motion; or we're latched and going the opposite way
-        let sameDir = (latchDir ^ offset) >= 0;
-        if (!aPref["latched"] || (isLatched ^ sameDir)) {
-          this._doAction(aEvent, [aGesture, offset > 0 ? aInc : aDec]);
-
-          // We must be getting latched or leaving it, so just toggle
-          isLatched = !isLatched;
-        }
-
-        // Reset motion counter to prepare for more of the same gesture
-        offset = 0;
-      }
-    };
-
-    // The start event also contains deltas, so handle an update right away
-    this._doUpdate(aEvent);
-  },
-
-  /**
-   * Checks whether a swipe gesture event can navigate the browser history or
-   * not.
-   *
-   * @param aEvent
-   *        The swipe gesture event.
-   * @return true if the swipe event may navigate the history, false othwerwise.
-   */
-  _swipeNavigatesHistory: function GS__swipeNavigatesHistory(aEvent) {
-    return this._getCommand(aEvent, ["swipe", "left"])
-              == "Browser:BackOrBackDuplicate" &&
-           this._getCommand(aEvent, ["swipe", "right"])
-              == "Browser:ForwardOrForwardDuplicate";
-  },
-
-  /**
-   * Checks whether we want to start a swipe for aEvent and sets
-   * aEvent.allowedDirections to the right values.
-   *
-   * @param aEvent
-   *        The swipe gesture "MayStart" event.
-   * @return true if we're willing to start a swipe for this event, false
-   *         otherwise.
-   */
-  _shouldDoSwipeGesture: function GS__shouldDoSwipeGesture(aEvent) {
-    if (!this._swipeNavigatesHistory(aEvent)) {
-      return false;
-    }
-
-    let isVerticalSwipe = false;
-    if (aEvent.direction == aEvent.DIRECTION_UP) {
-      if (gMultiProcessBrowser || content.pageYOffset > 0) {
-        return false;
-      }
-      isVerticalSwipe = true;
-    } else if (aEvent.direction == aEvent.DIRECTION_DOWN) {
-      if (gMultiProcessBrowser || content.pageYOffset < content.scrollMaxY) {
-        return false;
-      }
-      isVerticalSwipe = true;
-    }
-    if (isVerticalSwipe) {
-      // Vertical overscroll has been temporarily disabled until bug 939480 is
-      // fixed.
-      return false;
-    }
-
-    let canGoBack = gHistorySwipeAnimation.canGoBack();
-    let canGoForward = gHistorySwipeAnimation.canGoForward();
-    let isLTR = gHistorySwipeAnimation.isLTR;
-
-    if (canGoBack) {
-      aEvent.allowedDirections |= isLTR ? aEvent.DIRECTION_LEFT :
-                                          aEvent.DIRECTION_RIGHT;
-    }
-    if (canGoForward) {
-      aEvent.allowedDirections |= isLTR ? aEvent.DIRECTION_RIGHT :
-                                          aEvent.DIRECTION_LEFT;
-    }
-
-    return true;
-  },
-
-  /**
-   * Sets up swipe gestures. This includes setting up swipe animations for the
-   * gesture, if enabled.
-   *
-   * @param aEvent
-   *        The swipe gesture start event.
-   * @return true if swipe gestures could successfully be set up, false
-   *         othwerwise.
-   */
-  _setupSwipeGesture: function GS__setupSwipeGesture() {
-    gHistorySwipeAnimation.startAnimation(false);
-
-    this._doUpdate = function GS__doUpdate(aEvent) {
-      gHistorySwipeAnimation.updateAnimation(aEvent.delta);
-    };
-
-    this._doEnd = function GS__doEnd(aEvent) {
-      gHistorySwipeAnimation.swipeEndEventReceived();
-
-      this._doUpdate = function (aEvent) {};
-      this._doEnd = function (aEvent) {};
-    }
-  },
-
-  /**
-   * Generator producing the powerset of the input array where the first result
-   * is the complete set and the last result (before StopIteration) is empty.
-   *
-   * @param aArray
-   *        Source array containing any number of elements
-   * @yield Array that is a subset of the input array from full set to empty
-   */
-  _power: function* GS__power(aArray) {
-    // Create a bitmask based on the length of the array
-    let num = 1 << aArray.length;
-    while (--num >= 0) {
-      // Only select array elements where the current bit is set
-      yield aArray.reduce(function (aPrev, aCurr, aIndex) {
-        if (num & 1 << aIndex)
-          aPrev.push(aCurr);
-        return aPrev;
-      }, []);
-    }
-  },
-
-  /**
-   * Determine what action to do for the gesture based on which keys are
-   * pressed and which commands are set, and execute the command.
-   *
-   * @param aEvent
-   *        The original gesture event to convert into a fake click event
-   * @param aGesture
-   *        Array of gesture name parts (to be joined by periods)
-   * @return Name of the executed command. Returns null if no command is
-   *         found.
-   */
-  _doAction: function GS__doAction(aEvent, aGesture) {
-    let command = this._getCommand(aEvent, aGesture);
-    return command && this._doCommand(aEvent, command);
-  },
-
-  /**
-   * Determine what action to do for the gesture based on which keys are
-   * pressed and which commands are set
-   *
-   * @param aEvent
-   *        The original gesture event to convert into a fake click event
-   * @param aGesture
-   *        Array of gesture name parts (to be joined by periods)
-   */
-  _getCommand: function GS__getCommand(aEvent, aGesture) {
-    // Create an array of pressed keys in a fixed order so that a command for
-    // "meta" is preferred over "ctrl" when both buttons are pressed (and a
-    // command for both don't exist)
-    let keyCombos = [];
-    for (let key of ["shift", "alt", "ctrl", "meta"]) {
-      if (aEvent[key + "Key"])
-        keyCombos.push(key);
-    }
-
-    // Try each combination of key presses in decreasing order for commands
-    for (let subCombo of this._power(keyCombos)) {
-      // Convert a gesture and pressed keys into the corresponding command
-      // action where the preference has the gesture before "shift" before
-      // "alt" before "ctrl" before "meta" all separated by periods
-      let command;
-      try {
-        command = this._getPref(aGesture.concat(subCombo).join("."));
-      } catch (e) {}
-
-      if (command)
-        return command;
-    }
-    return null;
-  },
-
-  /**
-   * Execute the specified command.
-   *
-   * @param aEvent
-   *        The original gesture event to convert into a fake click event
-   * @param aCommand
-   *        Name of the command found for the event's keys and gesture.
-   */
-  _doCommand: function GS__doCommand(aEvent, aCommand) {
-    let node = document.getElementById(aCommand);
-    if (node) {
-      if (node.getAttribute("disabled") != "true") {
-        let cmdEvent = document.createEvent("xulcommandevent");
-        cmdEvent.initCommandEvent("command", true, true, window, 0,
-                                  aEvent.ctrlKey, aEvent.altKey,
-                                  aEvent.shiftKey, aEvent.metaKey, aEvent);
-        node.dispatchEvent(cmdEvent);
-      }
-
-    }
-    else {
-      goDoCommand(aCommand);
-    }
-  },
-
-  /**
-   * Handle continual motion events.  This function will be set by
-   * _setupGesture or _setupSwipe.
-   *
-   * @param aEvent
-   *        The continual motion update event to handle
-   */
-  _doUpdate: function(aEvent) {},
-
-  /**
-   * Handle gesture end events.  This function will be set by _setupSwipe.
-   *
-   * @param aEvent
-   *        The gesture end event to handle
-   */
-  _doEnd: function(aEvent) {},
-
-  /**
-   * Convert the swipe gesture into a browser action based on the direction.
-   *
-   * @param aEvent
-   *        The swipe event to handle
-   */
-  onSwipe: function GS_onSwipe(aEvent) {
-    // Figure out which one (and only one) direction was triggered
-    for (let dir of ["UP", "RIGHT", "DOWN", "LEFT"]) {
-      if (aEvent.direction == aEvent["DIRECTION_" + dir]) {
-        this._coordinateSwipeEventWithAnimation(aEvent, dir);
-        break;
-      }
-    }
-  },
-
-  /**
-   * Process a swipe event based on the given direction.
-   *
-   * @param aEvent
-   *        The swipe event to handle
-   * @param aDir
-   *        The direction for the swipe event
-   */
-  processSwipeEvent: function GS_processSwipeEvent(aEvent, aDir) {
-    this._doAction(aEvent, ["swipe", aDir.toLowerCase()]);
-  },
-
-  /**
-   * Coordinates the swipe event with the swipe animation, if any.
-   * If an animation is currently running, the swipe event will be
-   * processed once the animation stops. This will guarantee a fluid
-   * motion of the animation.
-   *
-   * @param aEvent
-   *        The swipe event to handle
-   * @param aDir
-   *        The direction for the swipe event
-   */
-  _coordinateSwipeEventWithAnimation:
-  function GS__coordinateSwipeEventWithAnimation(aEvent, aDir) {
-    if ((gHistorySwipeAnimation.isAnimationRunning()) &&
-        (aDir == "RIGHT" || aDir == "LEFT")) {
-      gHistorySwipeAnimation.processSwipeEvent(aEvent, aDir);
-    }
-    else {
-      this.processSwipeEvent(aEvent, aDir);
-    }
-  },
-
-  /**
-   * Get a gesture preference or use a default if it doesn't exist
-   *
-   * @param aPref
-   *        Name of the preference to load under the gesture branch
-   * @param aDef
-   *        Default value if the preference doesn't exist
-   */
-  _getPref: function GS__getPref(aPref, aDef) {
-    // Preferences branch under which all gestures preferences are stored
-    const branch = "browser.gesture.";
-
-    try {
-      // Determine what type of data to load based on default value's type
-      let type = typeof aDef;
-      let getFunc = "Char";
-      if (type == "boolean")
-        getFunc = "Bool";
-      else if (type == "number")
-        getFunc = "Int";
-      return gPrefService["get" + getFunc + "Pref"](branch + aPref);
-    }
-    catch (e) {
-      return aDef;
-    }
-  },
-
-  /**
-   * Perform rotation for ImageDocuments
-   *
-   * @param aEvent
-   *        The MozRotateGestureUpdate event triggering this call
-   */
-  rotate: function(aEvent) {
-    if (!(content.document instanceof ImageDocument))
-      return;
-
-    let contentElement = content.document.body.firstElementChild;
-    if (!contentElement)
-      return;
-    // If we're currently snapping, cancel that snap
-    if (contentElement.classList.contains("completeRotation"))
-      this._clearCompleteRotation();
-
-    this.rotation = Math.round(this.rotation + aEvent.delta);
-    contentElement.style.transform = "rotate(" + this.rotation + "deg)";
-    this._lastRotateDelta = aEvent.delta;
-  },
-
-  /**
-   * Perform a rotation end for ImageDocuments
-   */
-  rotateEnd: function() {
-    if (!(content.document instanceof ImageDocument))
-      return;
-
-    let contentElement = content.document.body.firstElementChild;
-    if (!contentElement)
-      return;
-
-    let transitionRotation = 0;
-
-    // The reason that 360 is allowed here is because when rotating between
-    // 315 and 360, setting rotate(0deg) will cause it to rotate the wrong
-    // direction around--spinning wildly.
-    if (this.rotation <= 45)
-      transitionRotation = 0;
-    else if (this.rotation > 45 && this.rotation <= 135)
-      transitionRotation = 90;
-    else if (this.rotation > 135 && this.rotation <= 225)
-      transitionRotation = 180;
-    else if (this.rotation > 225 && this.rotation <= 315)
-      transitionRotation = 270;
-    else
-      transitionRotation = 360;
-
-    // If we're going fast enough, and we didn't already snap ahead of rotation,
-    // then snap ahead of rotation to simulate momentum
-    if (this._lastRotateDelta > this._rotateMomentumThreshold &&
-        this.rotation > transitionRotation)
-      transitionRotation += 90;
-    else if (this._lastRotateDelta < -1 * this._rotateMomentumThreshold &&
-             this.rotation < transitionRotation)
-      transitionRotation -= 90;
-
-    // Only add the completeRotation class if it is is necessary
-    if (transitionRotation != this.rotation) {
-      contentElement.classList.add("completeRotation");
-      contentElement.addEventListener("transitionend", this._clearCompleteRotation);
-    }
-
-    contentElement.style.transform = "rotate(" + transitionRotation + "deg)";
-    this.rotation = transitionRotation;
-  },
-
-  /**
-   * Gets the current rotation for the ImageDocument
-   */
-  get rotation() {
-    return this._currentRotation;
-  },
-
-  /**
-   * Sets the current rotation for the ImageDocument
-   *
-   * @param aVal
-   *        The new value to take.  Can be any value, but it will be bounded to
-   *        0 inclusive to 360 exclusive.
-   */
-  set rotation(aVal) {
-    this._currentRotation = aVal % 360;
-    if (this._currentRotation < 0)
-      this._currentRotation += 360;
-    return this._currentRotation;
-  },
-
-  /**
-   * When the location/tab changes, need to reload the current rotation for the
-   * image
-   */
-  restoreRotationState: function() {
-    // Bug 863514 - Make gesture support work in electrolysis
-    if (gMultiProcessBrowser)
-      return;
-
-    if (!(content.document instanceof ImageDocument))
-      return;
-
-    let contentElement = content.document.body.firstElementChild;
-    let transformValue = content.window.getComputedStyle(contentElement, null)
-                                       .transform;
-
-    if (transformValue == "none") {
-      this.rotation = 0;
-      return;
-    }
-
-    // transformValue is a rotation matrix--split it and do mathemagic to
-    // obtain the real rotation value
-    transformValue = transformValue.split("(")[1]
-                                   .split(")")[0]
-                                   .split(",");
-    this.rotation = Math.round(Math.atan2(transformValue[1], transformValue[0]) *
-                               (180 / Math.PI));
-  },
-
-  /**
-   * Removes the transition rule by removing the completeRotation class
-   */
-  _clearCompleteRotation: function() {
-    let contentElement = content.document &&
-                         content.document instanceof ImageDocument &&
-                         content.document.body &&
-                         content.document.body.firstElementChild;
-    if (!contentElement)
-      return;
-    contentElement.classList.remove("completeRotation");
-    contentElement.removeEventListener("transitionend", this._clearCompleteRotation);
-  },
-};
-
-// History Swipe Animation Support (bug 678392)
-var gHistorySwipeAnimation = {
-
-  active: false,
-  isLTR: false,
-
-  /**
-   * Initializes the support for history swipe animations, if it is supported
-   * by the platform/configuration.
-   */
-  init: function HSA_init() {
-    if (!this._isSupported())
-      return;
-
-    this.active = false;
-    this.isLTR = document.documentElement.matches(":-moz-locale-dir(ltr)");
-    this._trackedSnapshots = [];
-    this._startingIndex = -1;
-    this._historyIndex = -1;
-    this._boxWidth = -1;
-    this._boxHeight = -1;
-    this._maxSnapshots = this._getMaxSnapshots();
-    this._lastSwipeDir = "";
-    this._direction = "horizontal";
-
-    // We only want to activate history swipe animations if we store snapshots.
-    // If we don't store any, we handle horizontal swipes without animations.
-    if (this._maxSnapshots > 0) {
-      this.active = true;
-      gBrowser.addEventListener("pagehide", this, false);
-      gBrowser.addEventListener("pageshow", this, false);
-      gBrowser.addEventListener("popstate", this, false);
-      gBrowser.addEventListener("DOMModalDialogClosed", this, false);
-      gBrowser.tabContainer.addEventListener("TabClose", this, false);
-    }
-  },
-
-  /**
-   * Uninitializes the support for history swipe animations.
-   */
-  uninit: function HSA_uninit() {
-    gBrowser.removeEventListener("pagehide", this, false);
-    gBrowser.removeEventListener("pageshow", this, false);
-    gBrowser.removeEventListener("popstate", this, false);
-    gBrowser.removeEventListener("DOMModalDialogClosed", this, false);
-    gBrowser.tabContainer.removeEventListener("TabClose", this, false);
-
-    this.active = false;
-    this.isLTR = false;
-  },
-
-  /**
-   * Starts the swipe animation and handles fast swiping (i.e. a swipe animation
-   * is already in progress when a new one is initiated).
-   *
-   * @param aIsVerticalSwipe
-   *        Whether we're dealing with a vertical swipe or not.
-   */
-  startAnimation: function HSA_startAnimation(aIsVerticalSwipe) {
-    this._direction = aIsVerticalSwipe ? "vertical" : "horizontal";
-
-    if (this.isAnimationRunning()) {
-      // If this is a horizontal scroll, or if this is a vertical scroll that
-      // was started while a horizontal scroll was still running, handle it as
-      // as a fast swipe. In the case of the latter scenario, this allows us to
-      // start the vertical animation without first loading the final page, or
-      // taking another snapshot. If vertical scrolls are initiated repeatedly
-      // without prior horizontal scroll we skip this and restart the animation
-      // from 0.
-      if (this._direction == "horizontal" || this._lastSwipeDir != "") {
-        gBrowser.stop();
-        this._lastSwipeDir = "RELOAD"; // just ensure that != ""
-        this._canGoBack = this.canGoBack();
-        this._canGoForward = this.canGoForward();
-        this._handleFastSwiping();
-      }
-      this.updateAnimation(0);
-    }
-    else {
-      // Get the session history from SessionStore.
-      let updateSessionHistory = sessionHistory => {
-        this._startingIndex = sessionHistory.index;
-        this._historyIndex = this._startingIndex;
-        this._canGoBack = this.canGoBack();
-        this._canGoForward = this.canGoForward();
-        if (this.active) {
-          this._addBoxes();
-          this._takeSnapshot();
-          this._installPrevAndNextSnapshots();
-          this._lastSwipeDir = "";
-        }
-        this.updateAnimation(0);
-      }
-      SessionStore.getSessionHistory(gBrowser.selectedTab, updateSessionHistory);
-    }
-  },
-
-  /**
-   * Stops the swipe animation.
-   */
-  stopAnimation: function HSA_stopAnimation() {
-    gHistorySwipeAnimation._removeBoxes();
-    this._historyIndex = this._getCurrentHistoryIndex();
-  },
-
-  /**
-   * Updates the animation between two pages in history.
-   *
-   * @param aVal
-   *        A floating point value that represents the progress of the
-   *        swipe gesture.
-   */
-  updateAnimation: function HSA_updateAnimation(aVal) {
-    if (!this.isAnimationRunning()) {
-      return;
-    }
-
-    // We use the following value to decrease the bounce effect when scrolling
-    // to the top or bottom of the page, or when swiping back/forward past the
-    // browsing history. This value was determined experimentally.
-    let dampValue = 4;
-    if (this._direction == "vertical") {
-      this._prevBox.collapsed = true;
-      this._nextBox.collapsed = true;
-      this._positionBox(this._curBox, -1 * aVal / dampValue);
-    } else if ((aVal >= 0 && this.isLTR) ||
-               (aVal <= 0 && !this.isLTR)) {
-      let tempDampValue = 1;
-      if (this._canGoBack) {
-        this._prevBox.collapsed = false;
-      } else {
-        tempDampValue = dampValue;
-        this._prevBox.collapsed = true;
-      }
-
-      // The current page is pushed to the right (LTR) or left (RTL),
-      // the intention is to go back.
-      // If there is a page to go back to, it should show in the background.
-      this._positionBox(this._curBox, aVal / tempDampValue);
-
-      // The forward page should be pushed offscreen all the way to the right.
-      this._positionBox(this._nextBox, 1);
-    } else if (this._canGoForward) {
-      // The intention is to go forward. If there is a page to go forward to,
-      // it should slide in from the right (LTR) or left (RTL).
-      // Otherwise, the current page should slide to the left (LTR) or
-      // right (RTL) and the backdrop should appear in the background.
-      // For the backdrop to be visible in that case, the previous page needs
-      // to be hidden (if it exists).
-      this._nextBox.collapsed = false;
-      let offset = this.isLTR ? 1 : -1;
-      this._positionBox(this._curBox, 0);
-      this._positionBox(this._nextBox, offset + aVal);
-    } else {
-      this._prevBox.collapsed = true;
-      this._positionBox(this._curBox, aVal / dampValue);
-    }
-  },
-
-  _getCurrentHistoryIndex: function() {
-    return SessionStore.getSessionHistory(gBrowser.selectedTab).index;
-  },
-
-  /**
-   * Event handler for events relevant to the history swipe animation.
-   *
-   * @param aEvent
-   *        An event to process.
-   */
-  handleEvent: function HSA_handleEvent(aEvent) {
-    let browser = gBrowser.selectedBrowser;
-    switch (aEvent.type) {
-      case "TabClose":
-        let browserForTab = gBrowser.getBrowserForTab(aEvent.target);
-        this._removeTrackedSnapshot(-1, browserForTab);
-        break;
-      case "DOMModalDialogClosed":
-        this.stopAnimation();
-        break;
-      case "pageshow":
-        if (aEvent.target == browser.contentDocument) {
-          this.stopAnimation();
-        }
-        break;
-      case "popstate":
-        if (aEvent.target == browser.contentDocument.defaultView) {
-          this.stopAnimation();
-        }
-        break;
-      case "pagehide":
-        if (aEvent.target == browser.contentDocument) {
-          // Take and compress a snapshot of a page whenever it's about to be
-          // navigated away from. We already have a snapshot of the page if an
-          // animation is running, so we're left with compressing it.
-          if (!this.isAnimationRunning()) {
-            this._takeSnapshot();
-          }
-          this._compressSnapshotAtCurrentIndex();
-        }
-        break;
-    }
-  },
-
-  /**
-   * Checks whether the history swipe animation is currently running or not.
-   *
-   * @return true if the animation is currently running, false otherwise.
-   */
-  isAnimationRunning: function HSA_isAnimationRunning() {
-    return !!this._container;
-  },
-
-  /**
-   * Process a swipe event based on the given direction.
-   *
-   * @param aEvent
-   *        The swipe event to handle
-   * @param aDir
-   *        The direction for the swipe event
-   */
-  processSwipeEvent: function HSA_processSwipeEvent(aEvent, aDir) {
-    if (aDir == "RIGHT")
-      this._historyIndex += this.isLTR ? 1 : -1;
-    else if (aDir == "LEFT")
-      this._historyIndex += this.isLTR ? -1 : 1;
-    else
-      return;
-    this._lastSwipeDir = aDir;
-  },
-
-  /**
-   * Checks if there is a page in the browser history to go back to.
-   *
-   * @return true if there is a previous page in history, false otherwise.
-   */
-  canGoBack: function HSA_canGoBack() {
-    if (this.isAnimationRunning())
-      return this._doesIndexExistInHistory(this._historyIndex - 1);
-    return gBrowser.webNavigation.canGoBack;
-  },
-
-  /**
-   * Checks if there is a page in the browser history to go forward to.
-   *
-   * @return true if there is a next page in history, false otherwise.
-   */
-  canGoForward: function HSA_canGoForward() {
-    if (this.isAnimationRunning())
-      return this._doesIndexExistInHistory(this._historyIndex + 1);
-    return gBrowser.webNavigation.canGoForward;
-  },
-
-  /**
-   * Used to notify the history swipe animation that the OS sent a swipe end
-   * event and that we should navigate to the page that the user swiped to, if
-   * any. This will also result in the animation overlay to be torn down.
-   */
-  swipeEndEventReceived: function HSA_swipeEndEventReceived() {
-    // Update the session history before continuing.
-    let updateSessionHistory = sessionHistory => {
-      if (this._lastSwipeDir != "" && this._historyIndex != this._startingIndex)
-        this._navigateToHistoryIndex();
-      else
-        this.stopAnimation();
-    }
-    SessionStore.getSessionHistory(gBrowser.selectedTab, updateSessionHistory);
-  },
-
-  /**
-   * Checks whether a particular index exists in the browser history or not.
-   *
-   * @param aIndex
-   *        The index to check for availability for in the history.
-   * @return true if the index exists in the browser history, false otherwise.
-   */
-  _doesIndexExistInHistory: function HSA__doesIndexExistInHistory(aIndex) {
-    try {
-      return SessionStore.getSessionHistory(gBrowser.selectedTab).entries[aIndex] != null;
-    }
-    catch (ex) {
-      return false;
-    }
-  },
-
-  /**
-   * Navigates to the index in history that is currently being tracked by
-   * |this|.
-   */
-  _navigateToHistoryIndex: function HSA__navigateToHistoryIndex() {
-    if (this._doesIndexExistInHistory(this._historyIndex))
-      gBrowser.webNavigation.gotoIndex(this._historyIndex);
-    else
-      this.stopAnimation();
-  },
-
-  /**
-   * Checks to see if history swipe animations are supported by this
-   * platform/configuration.
-   *
-   * return true if supported, false otherwise.
-   */
-  _isSupported: function HSA__isSupported() {
-    return window.matchMedia("(-moz-swipe-animation-enabled)").matches;
-  },
-
-  /**
-   * Handle fast swiping (i.e. a swipe animation is already in
-   * progress when a new one is initiated). This will swap out the snapshots
-   * used in the previous animation with the appropriate new ones.
-   */
-  _handleFastSwiping: function HSA__handleFastSwiping() {
-    this._installCurrentPageSnapshot(null);
-    this._installPrevAndNextSnapshots();
-  },
-
-  /**
-   * Adds the boxes that contain the snapshots used during the swipe animation.
-   */
-  _addBoxes: function HSA__addBoxes() {
-    let browserStack =
-      document.getAnonymousElementByAttribute(gBrowser.getNotificationBox(),
-                                              "class", "browserStack");
-    this._container = this._createElement("historySwipeAnimationContainer",
-                                          "stack");
-    browserStack.appendChild(this._container);
-
-    this._prevBox = this._createElement("historySwipeAnimationPreviousPage",
-                                        "box");
-    this._container.appendChild(this._prevBox);
-
-    this._curBox = this._createElement("historySwipeAnimationCurrentPage",
-                                       "box");
-    this._container.appendChild(this._curBox);
-
-    this._nextBox = this._createElement("historySwipeAnimationNextPage",
-                                        "box");
-    this._container.appendChild(this._nextBox);
-
-    // Cache width and height.
-    this._boxWidth = this._curBox.getBoundingClientRect().width;
-    this._boxHeight = this._curBox.getBoundingClientRect().height;
-  },
-
-  /**
-   * Removes the boxes.
-   */
-  _removeBoxes: function HSA__removeBoxes() {
-    this._curBox = null;
-    this._prevBox = null;
-    this._nextBox = null;
-    if (this._container)
-      this._container.parentNode.removeChild(this._container);
-    this._container = null;
-    this._boxWidth = -1;
-    this._boxHeight = -1;
-  },
-
-  /**
-   * Creates an element with a given identifier and tag name.
-   *
-   * @param aID
-   *        An identifier to create the element with.
-   * @param aTagName
-   *        The name of the tag to create the element for.
-   * @return the newly created element.
-   */
-  _createElement: function HSA__createElement(aID, aTagName) {
-    let XULNS = "http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul";
-    let element = document.createElementNS(XULNS, aTagName);
-    element.id = aID;
-    return element;
-  },
-
-  /**
-   * Moves a given box to a given X coordinate position.
-   *
-   * @param aBox
-   *        The box element to position.
-   * @param aPosition
-   *        The position (in X coordinates) to move the box element to.
-   */
-  _positionBox: function HSA__positionBox(aBox, aPosition) {
-    let transform = "";
-
-    if (this._direction == "vertical")
-      transform = "translateY(" + this._boxHeight * aPosition + "px)";
-    else
-      transform = "translateX(" + this._boxWidth * aPosition + "px)";
-
-    aBox.style.transform = transform;
-  },
-
-  /**
-   * Verifies that we're ready to take snapshots based on the global pref and
-   * the current index in history.
-   *
-   * @return true if we're ready to take snapshots, false otherwise.
-   */
-  _readyToTakeSnapshots: function HSA__readyToTakeSnapshots() {
-    return (this._maxSnapshots >= 1 && this._getCurrentHistoryIndex() >= 0);
-  },
-
-  /**
-   * Takes a snapshot of the page the browser is currently on.
-   */
-  _takeSnapshot: function HSA__takeSnapshot() {
-    if (!this._readyToTakeSnapshots()) {
-      return;
-    }
-
-    let canvas = null;
-
-    let browser = gBrowser.selectedBrowser;
-    let r = browser.getBoundingClientRect();
-    canvas = document.createElementNS("http://www.w3.org/1999/xhtml",
-                                      "canvas");
-    canvas.mozOpaque = true;
-    let scale = window.devicePixelRatio;
-    canvas.width = r.width * scale;
-    canvas.height = r.height * scale;
-    let ctx = canvas.getContext("2d");
-    let zoom = browser.markupDocumentViewer.fullZoom * scale;
-    ctx.scale(zoom, zoom);
-    ctx.drawWindow(browser.contentWindow,
-                   0, 0, canvas.width / zoom, canvas.height / zoom, "white",
-                   ctx.DRAWWINDOW_DO_NOT_FLUSH | ctx.DRAWWINDOW_DRAW_VIEW |
-                   ctx.DRAWWINDOW_ASYNC_DECODE_IMAGES |
-                   ctx.DRAWWINDOW_USE_WIDGET_LAYERS);
-
-    TelemetryStopwatch.start("FX_GESTURE_INSTALL_SNAPSHOT_OF_PAGE");
-    try {
-      this._installCurrentPageSnapshot(canvas);
-      this._assignSnapshotToCurrentBrowser(canvas);
-    } finally {
-      TelemetryStopwatch.finish("FX_GESTURE_INSTALL_SNAPSHOT_OF_PAGE");
-    }
-  },
-
-  /**
-   * Retrieves the maximum number of snapshots that should be kept in memory.
-   * This limit is a global limit and is valid across all open tabs.
-   */
-  _getMaxSnapshots: function HSA__getMaxSnapshots() {
-    return gPrefService.getIntPref("browser.snapshots.limit");
-  },
-
-  /**
-   * Adds a snapshot to the list and initiates the compression of said snapshot.
-   * Once the compression is completed, it will replace the uncompressed
-   * snapshot in the list.
-   *
-   * @param aCanvas
-   *        The snapshot to add to the list and compress.
-   */
-  _assignSnapshotToCurrentBrowser:
-  function HSA__assignSnapshotToCurrentBrowser(aCanvas) {
-    let browser = gBrowser.selectedBrowser;
-    let currIndex = this._getCurrentHistoryIndex();
-
-    this._removeTrackedSnapshot(currIndex, browser);
-    this._addSnapshotRefToArray(currIndex, browser);
-
-    if (!("snapshots" in browser))
-      browser.snapshots = [];
-    let snapshots = browser.snapshots;
-    // Temporarily store the canvas as the compressed snapshot.
-    // This avoids a blank page if the user swipes quickly
-    // between pages before the compression could complete.
-    snapshots[currIndex] = {
-      image: aCanvas,
-      scale: window.devicePixelRatio
-    };
-  },
-
-  /**
-   * Compresses the HTMLCanvasElement that's stored at the current history
-   * index in the snapshot array and stores the compressed image in its place.
-   */
-  _compressSnapshotAtCurrentIndex:
-  function HSA__compressSnapshotAtCurrentIndex() {
-    if (!this._readyToTakeSnapshots()) {
-      // We didn't take a snapshot earlier because we weren't ready to, so
-      // there's nothing to compress.
-      return;
-    }
-
-    TelemetryStopwatch.start("FX_GESTURE_COMPRESS_SNAPSHOT_OF_PAGE");
-    try {
-      let browser = gBrowser.selectedBrowser;
-      let snapshots = browser.snapshots;
-      let currIndex = _getCurrentHistoryIndex();
-
-      // Kick off snapshot compression.
-      let canvas = snapshots[currIndex].image;
-      canvas.toBlob(function(aBlob) {
-          if (snapshots[currIndex]) {
-            snapshots[currIndex].image = aBlob;
-          }
-        }, "image/png"
-      );
-    } finally {
-      TelemetryStopwatch.finish("FX_GESTURE_COMPRESS_SNAPSHOT_OF_PAGE");
-    }
-  },
-
-  /**
-   * Removes a snapshot identified by the browser and index in the array of
-   * snapshots for that browser, if present. If no snapshot could be identified
-   * the method simply returns without taking any action. If aIndex is negative,
-   * all snapshots for a particular browser will be removed.
-   *
-   * @param aIndex
-   *        The index in history of the new snapshot, or negative value if all
-   *        snapshots for a browser should be removed.
-   * @param aBrowser
-   *        The browser the new snapshot was taken in.
-   */
-  _removeTrackedSnapshot: function HSA__removeTrackedSnapshot(aIndex, aBrowser) {
-    let arr = this._trackedSnapshots;
-    let requiresExactIndexMatch = aIndex >= 0;
-    for (let i = 0; i < arr.length; i++) {
-      if ((arr[i].browser == aBrowser) &&
-          (aIndex < 0 || aIndex == arr[i].index)) {
-        delete aBrowser.snapshots[arr[i].index];
-        arr.splice(i, 1);
-        if (requiresExactIndexMatch)
-          return; // Found and removed the only element.
-        i--; // Make sure to revisit the index that we just removed an
-             // element at.
-      }
-    }
-  },
-
-  /**
-   * Adds a new snapshot reference for a given index and browser to the array
-   * of references to tracked snapshots.
-   *
-   * @param aIndex
-   *        The index in history of the new snapshot.
-   * @param aBrowser
-   *        The browser the new snapshot was taken in.
-   */
-  _addSnapshotRefToArray:
-  function HSA__addSnapshotRefToArray(aIndex, aBrowser) {
-    let id = { index: aIndex,
-               browser: aBrowser };
-    let arr = this._trackedSnapshots;
-    arr.unshift(id);
-
-    while (arr.length > this._maxSnapshots) {
-      let lastElem = arr[arr.length - 1];
-      delete lastElem.browser.snapshots[lastElem.index].image;
-      delete lastElem.browser.snapshots[lastElem.index];
-      arr.splice(-1, 1);
-    }
-  },
-
-  /**
-   * Converts a compressed blob to an Image object. In some situations
-   * (especially during fast swiping) aBlob may still be a canvas, not a
-   * compressed blob. In this case, we simply return the canvas.
-   *
-   * @param aBlob
-   *        The compressed blob to convert, or a canvas if a blob compression
-   *        couldn't complete before this method was called.
-   * @return A new Image object representing the converted blob.
-   */
-  _convertToImg: function HSA__convertToImg(aBlob) {
-    if (!aBlob)
-      return null;
-
-    // Return aBlob if it's still a canvas and not a compressed blob yet.
-    if (aBlob instanceof HTMLCanvasElement)
-      return aBlob;
-
-    let img = new Image();
-    let url = "";
-    try {
-      url = URL.createObjectURL(aBlob);
-      img.onload = function() {
-        URL.revokeObjectURL(url);
-      };
-    }
-    finally {
-      img.src = url;
-      return img;
-    }
-  },
-
-  /**
-   * Scales the background of a given box element (which uses a given snapshot
-   * as background) based on a given scale factor.
-   * @param aSnapshot
-   *        The snapshot that is used as background of aBox.
-   * @param aScale
-   *        The scale factor to use.
-   * @param aBox
-   *        The box element that uses aSnapshot as background.
-   */
-  _scaleSnapshot: function HSA__scaleSnapshot(aSnapshot, aScale, aBox) {
-    if (aSnapshot && aScale != 1 && aBox) {
-      if (aSnapshot instanceof HTMLCanvasElement) {
-        aBox.style.backgroundSize =
-          aSnapshot.width / aScale + "px " + aSnapshot.height / aScale + "px";
-      } else {
-        // snapshot is instanceof HTMLImageElement
-        aSnapshot.addEventListener("load", function() {
-          aBox.style.backgroundSize =
-            aSnapshot.width / aScale + "px " + aSnapshot.height / aScale + "px";
-        });
-      }
-    }
-  },
-
-  /**
-   * Sets the snapshot of the current page to the snapshot passed as parameter,
-   * or to the one previously stored for the current index in history if the
-   * parameter is null.
-   *
-   * @param aCanvas
-   *        The snapshot to set the current page to. If this parameter is null,
-   *        the previously stored snapshot for this index (if any) will be used.
-   */
-  _installCurrentPageSnapshot:
-  function HSA__installCurrentPageSnapshot(aCanvas) {
-    let currSnapshot = aCanvas;
-    let scale = window.devicePixelRatio;
-    if (!currSnapshot) {
-      let snapshots = gBrowser.selectedBrowser.snapshots || {};
-      let currIndex = this._historyIndex;
-      if (currIndex in snapshots) {
-        currSnapshot = this._convertToImg(snapshots[currIndex].image);
-        scale = snapshots[currIndex].scale;
-      }
-    }
-    this._scaleSnapshot(currSnapshot, scale, this._curBox ? this._curBox :
-                                                            null);
-    document.mozSetImageElement("historySwipeAnimationCurrentPageSnapshot",
-                                currSnapshot);
-  },
-
-  /**
-   * Sets the snapshots of the previous and next pages to the snapshots
-   * previously stored for their respective indeces.
-   */
-  _installPrevAndNextSnapshots:
-  function HSA__installPrevAndNextSnapshots() {
-    let snapshots = gBrowser.selectedBrowser.snapshots || [];
-    let currIndex = this._historyIndex;
-    let prevIndex = currIndex - 1;
-    let prevSnapshot = null;
-    if (prevIndex in snapshots) {
-      prevSnapshot = this._convertToImg(snapshots[prevIndex].image);
-      this._scaleSnapshot(prevSnapshot, snapshots[prevIndex].scale,
-                          this._prevBox);
-    }
-    document.mozSetImageElement("historySwipeAnimationPreviousPageSnapshot",
-                                prevSnapshot);
-
-    let nextIndex = currIndex + 1;
-    let nextSnapshot = null;
-    if (nextIndex in snapshots) {
-      nextSnapshot = this._convertToImg(snapshots[nextIndex].image);
-      this._scaleSnapshot(nextSnapshot, snapshots[nextIndex].scale,
-                          this._nextBox);
-    }
-    document.mozSetImageElement("historySwipeAnimationNextPageSnapshot",
-                                nextSnapshot);
-  },
-};