DevTools: reformat front-end code to match chromium style.

third_party/WebKit/Source/devtools/front_end/timeline_model/TracingLayerTree.js

Index: third_party/WebKit/Source/devtools/front_end/timeline_model/TracingLayerTree.js
diff --git a/third_party/WebKit/Source/devtools/front_end/timeline_model/TracingLayerTree.js b/third_party/WebKit/Source/devtools/front_end/timeline_model/TracingLayerTree.js
index f5b4372e679503709cd9ec9b4efa4bb3ec1f3ec0..0182f703f10905b2e3d2638e41ac5cf49115102a 100644
--- a/third_party/WebKit/Source/devtools/front_end/timeline_model/TracingLayerTree.js
+++ b/third_party/WebKit/Source/devtools/front_end/timeline_model/TracingLayerTree.js
@@ -1,7 +1,6 @@
 // Copyright 2016 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
-
 /** @typedef {!{
         bounds: {height: number, width: number},
         children: Array.<!WebInspector.TracingLayerPayload>,
@@ -35,480 +34,447 @@ WebInspector.TracingLayerTile;
 WebInspector.SnapshotWithRect;
 
 /**
-  * @constructor
-  * @extends {WebInspector.LayerTreeBase}
-  * @param {?WebInspector.Target} target
-  */
-WebInspector.TracingLayerTree = function(target)
-{
-    WebInspector.LayerTreeBase.call(this, target);
+ * @unrestricted
+ */
+WebInspector.TracingLayerTree = class extends WebInspector.LayerTreeBase {
+  /**
+   * @param {?WebInspector.Target} target
+   */
+  constructor(target) {
+    super(target);
     /** @type {!Map.<string, !WebInspector.TracingLayerTile>} */
     this._tileById = new Map();
-};
-
-WebInspector.TracingLayerTree.prototype = {
-    /**
-     * @param {?WebInspector.TracingLayerPayload} root
-     * @param {?Array<!WebInspector.TracingLayerPayload>} layers
-     * @param {!Array<!WebInspector.LayerPaintEvent>} paints
-     * @param {function()} callback
-     */
-    setLayers: function(root, layers, paints, callback)
-    {
-        var idsToResolve = new Set();
-        if (root) {
-            // This is a legacy code path for compatibility, as cc is removing
-            // layer tree hierarchy, this code will eventually be removed.
-            this._extractNodeIdsToResolve(idsToResolve, {}, root);
-        } else {
-            for (var i = 0; i < layers.length; ++i)
-                this._extractNodeIdsToResolve(idsToResolve, {}, layers[i]);
-        }
-        this._resolveBackendNodeIds(idsToResolve, onBackendNodeIdsResolved.bind(this));
-
-        /**
-         * @this {WebInspector.TracingLayerTree}
-         */
-        function onBackendNodeIdsResolved()
-        {
-            var oldLayersById = this._layersById;
-            this._layersById = {};
-            this.setContentRoot(null);
-            if (root) {
-                var convertedLayers = this._innerSetLayers(oldLayersById, root);
-                this.setRoot(convertedLayers);
-            } else {
-                var processedLayers = layers.map(this._innerSetLayers.bind(this, oldLayersById));
-                var contentRoot = this.contentRoot();
-                this.setRoot(contentRoot);
-                for (var i = 0; i < processedLayers.length; ++i) {
-                    if (processedLayers[i].id() !== contentRoot.id())
-                        contentRoot.addChild(processedLayers[i]);
-                }
-            }
-            this._setPaints(paints);
-            callback();
-        }
-    },
-
-    /**
-     * @param {!Array.<!WebInspector.TracingLayerTile>} tiles
-     */
-    setTiles: function(tiles)
-    {
-        this._tileById = new Map();
-        for (var tile of tiles)
-            this._tileById.set(tile.id, tile);
-    },
-
-    /**
-     * @param {string} tileId
-     * @return {!Promise<?WebInspector.SnapshotWithRect>}
-     */
-    pictureForRasterTile: function(tileId)
-    {
-        var tile = this._tileById.get("cc::Tile/" + tileId);
-        if (!tile) {
-            WebInspector.console.error(`Tile ${tileId} is missing`);
-            return /** @type {!Promise<?WebInspector.SnapshotWithRect>} */ (Promise.resolve(null));
-        }
-        var layer = this.layerById(tile.layer_id);
-        if (!layer) {
-            WebInspector.console.error(`Layer ${tile.layer_id} for tile ${tileId} is not found`);
-            return /** @type {!Promise<?WebInspector.SnapshotWithRect>} */ (Promise.resolve(null));
-        }
-        return layer._pictureForRect(tile.content_rect);
-    },
-
-    /**
-     * @param {!Array<!WebInspector.LayerPaintEvent>} paints
-     */
-    _setPaints: function(paints)
-    {
-        for (var i = 0; i < paints.length; ++i) {
-            var layer = this._layersById[paints[i].layerId()];
-            if (layer)
-                layer._addPaintEvent(paints[i]);
+  }
+
+  /**
+   * @param {?WebInspector.TracingLayerPayload} root
+   * @param {?Array<!WebInspector.TracingLayerPayload>} layers
+   * @param {!Array<!WebInspector.LayerPaintEvent>} paints
+   * @param {function()} callback
+   */
+  setLayers(root, layers, paints, callback) {
+    var idsToResolve = new Set();
+    if (root) {
+      // This is a legacy code path for compatibility, as cc is removing
+      // layer tree hierarchy, this code will eventually be removed.
+      this._extractNodeIdsToResolve(idsToResolve, {}, root);
+    } else {
+      for (var i = 0; i < layers.length; ++i)
+        this._extractNodeIdsToResolve(idsToResolve, {}, layers[i]);
+    }
+    this._resolveBackendNodeIds(idsToResolve, onBackendNodeIdsResolved.bind(this));
+
+    /**
+     * @this {WebInspector.TracingLayerTree}
+     */
+    function onBackendNodeIdsResolved() {
+      var oldLayersById = this._layersById;
+      this._layersById = {};
+      this.setContentRoot(null);
+      if (root) {
+        var convertedLayers = this._innerSetLayers(oldLayersById, root);
+        this.setRoot(convertedLayers);
+      } else {
+        var processedLayers = layers.map(this._innerSetLayers.bind(this, oldLayersById));
+        var contentRoot = this.contentRoot();
+        this.setRoot(contentRoot);
+        for (var i = 0; i < processedLayers.length; ++i) {
+          if (processedLayers[i].id() !== contentRoot.id())
+            contentRoot.addChild(processedLayers[i]);
         }
-    },
-
-    /**
-     * @param {!Object<(string|number), !WebInspector.Layer>} oldLayersById
-     * @param {!WebInspector.TracingLayerPayload} payload
-     * @return {!WebInspector.TracingLayer}
-     */
-    _innerSetLayers: function(oldLayersById, payload)
-    {
-        var layer = /** @type {?WebInspector.TracingLayer} */ (oldLayersById[payload.layer_id]);
-        if (layer)
-            layer._reset(payload);
-        else
-            layer = new WebInspector.TracingLayer(this.target(), payload);
-        this._layersById[payload.layer_id] = layer;
-        if (payload.owner_node)
-            layer._setNode(this._backendNodeIdToNode.get(payload.owner_node) || null);
-        if (!this.contentRoot() && layer.drawsContent())
-            this.setContentRoot(layer);
-        for (var i = 0; payload.children && i < payload.children.length; ++i)
-            layer.addChild(this._innerSetLayers(oldLayersById, payload.children[i]));
-        return layer;
-    },
+      }
+      this._setPaints(paints);
+      callback();
+    }
+  }
 
-    /**
-     * @param {!Set<number>} nodeIdsToResolve
-     * @param {!Object} seenNodeIds
-     * @param {!WebInspector.TracingLayerPayload} payload
-     */
-    _extractNodeIdsToResolve: function(nodeIdsToResolve, seenNodeIds, payload)
-    {
-        var backendNodeId = payload.owner_node;
-        if (backendNodeId && !this._backendNodeIdToNode.has(backendNodeId))
-            nodeIdsToResolve.add(backendNodeId);
-        for (var i = 0; payload.children && i < payload.children.length; ++i)
-            this._extractNodeIdsToResolve(nodeIdsToResolve, seenNodeIds, payload.children[i]);
-    },
-
-    __proto__: WebInspector.LayerTreeBase.prototype
+  /**
+   * @param {!Array.<!WebInspector.TracingLayerTile>} tiles
+   */
+  setTiles(tiles) {
+    this._tileById = new Map();
+    for (var tile of tiles)
+      this._tileById.set(tile.id, tile);
+  }
+
+  /**
+   * @param {string} tileId
+   * @return {!Promise<?WebInspector.SnapshotWithRect>}
+   */
+  pictureForRasterTile(tileId) {
+    var tile = this._tileById.get('cc::Tile/' + tileId);
+    if (!tile) {
+      WebInspector.console.error(`Tile ${tileId} is missing`);
+      return /** @type {!Promise<?WebInspector.SnapshotWithRect>} */ (Promise.resolve(null));
+    }
+    var layer = this.layerById(tile.layer_id);
+    if (!layer) {
+      WebInspector.console.error(`Layer ${tile.layer_id} for tile ${tileId} is not found`);
+      return /** @type {!Promise<?WebInspector.SnapshotWithRect>} */ (Promise.resolve(null));
+    }
+    return layer._pictureForRect(tile.content_rect);
+  }
+
+  /**
+   * @param {!Array<!WebInspector.LayerPaintEvent>} paints
+   */
+  _setPaints(paints) {
+    for (var i = 0; i < paints.length; ++i) {
+      var layer = this._layersById[paints[i].layerId()];
+      if (layer)
+        layer._addPaintEvent(paints[i]);
+    }
+  }
+
+  /**
+   * @param {!Object<(string|number), !WebInspector.Layer>} oldLayersById
+   * @param {!WebInspector.TracingLayerPayload} payload
+   * @return {!WebInspector.TracingLayer}
+   */
+  _innerSetLayers(oldLayersById, payload) {
+    var layer = /** @type {?WebInspector.TracingLayer} */ (oldLayersById[payload.layer_id]);
+    if (layer)
+      layer._reset(payload);
+    else
+      layer = new WebInspector.TracingLayer(this.target(), payload);
+    this._layersById[payload.layer_id] = layer;
+    if (payload.owner_node)
+      layer._setNode(this._backendNodeIdToNode.get(payload.owner_node) || null);
+    if (!this.contentRoot() && layer.drawsContent())
+      this.setContentRoot(layer);
+    for (var i = 0; payload.children && i < payload.children.length; ++i)
+      layer.addChild(this._innerSetLayers(oldLayersById, payload.children[i]));
+    return layer;
+  }
+
+  /**
+   * @param {!Set<number>} nodeIdsToResolve
+   * @param {!Object} seenNodeIds
+   * @param {!WebInspector.TracingLayerPayload} payload
+   */
+  _extractNodeIdsToResolve(nodeIdsToResolve, seenNodeIds, payload) {
+    var backendNodeId = payload.owner_node;
+    if (backendNodeId && !this._backendNodeIdToNode.has(backendNodeId))
+      nodeIdsToResolve.add(backendNodeId);
+    for (var i = 0; payload.children && i < payload.children.length; ++i)
+      this._extractNodeIdsToResolve(nodeIdsToResolve, seenNodeIds, payload.children[i]);
+  }
 };
 
 /**
- * @constructor
- * @param {!WebInspector.TracingLayerPayload} payload
- * @param {?WebInspector.Target} target
  * @implements {WebInspector.Layer}
+ * @unrestricted
  */
-WebInspector.TracingLayer = function(target, payload)
-{
+WebInspector.TracingLayer = class {
+  /**
+   * @param {!WebInspector.TracingLayerPayload} payload
+   * @param {?WebInspector.Target} target
+   */
+  constructor(target, payload) {
     this._target = target;
     this._reset(payload);
-};
-
-WebInspector.TracingLayer.prototype = {
-    /**
-     * @param {!WebInspector.TracingLayerPayload} payload
-     */
-    _reset: function(payload)
-    {
-        /** @type {?WebInspector.DOMNode} */
-        this._node = null;
-        this._layerId = String(payload.layer_id);
-        this._offsetX = payload.position[0];
-        this._offsetY = payload.position[1];
-        this._width = payload.bounds.width;
-        this._height = payload.bounds.height;
-        this._children = [];
-        this._parentLayerId = null;
-        this._parent = null;
-        this._quad = payload.layer_quad || [];
-        this._createScrollRects(payload);
-        this._compositingReasons = payload.compositing_reasons || [];
-        this._drawsContent = !!payload.draws_content;
-        this._gpuMemoryUsage = payload.gpu_memory_usage;
-        this._paints = [];
-    },
-
-    /**
-     * @override
-     * @return {string}
-     */
-    id: function()
-    {
-        return this._layerId;
-    },
-
-    /**
-     * @override
-     * @return {?string}
-     */
-    parentId: function()
-    {
-        return this._parentLayerId;
-    },
-
-    /**
-     * @override
-     * @return {?WebInspector.Layer}
-     */
-    parent: function()
-    {
-        return this._parent;
-    },
-
-    /**
-     * @override
-     * @return {boolean}
-     */
-    isRoot: function()
-    {
-        return !this.parentId();
-    },
-
-    /**
-     * @override
-     * @return {!Array.<!WebInspector.Layer>}
-     */
-    children: function()
-    {
-        return this._children;
-    },
-
-    /**
-     * @override
-     * @param {!WebInspector.Layer} child
-     */
-    addChild: function(child)
-    {
-        if (child._parent)
-            console.assert(false, "Child already has a parent");
-        this._children.push(child);
-        child._parent = this;
-        child._parentLayerId = this._layerId;
-    },
-
-
-    /**
-     * @param {?WebInspector.DOMNode} node
-     */
-    _setNode: function(node)
-    {
-        this._node = node;
-    },
-
-    /**
-     * @override
-     * @return {?WebInspector.DOMNode}
-     */
-    node: function()
-    {
-        return this._node;
-    },
-
-    /**
-     * @override
-     * @return {?WebInspector.DOMNode}
-     */
-    nodeForSelfOrAncestor: function()
-    {
-        for (var layer = this; layer; layer = layer._parent) {
-            if (layer._node)
-                return layer._node;
-        }
+  }
+
+  /**
+   * @param {!WebInspector.TracingLayerPayload} payload
+   */
+  _reset(payload) {
+    /** @type {?WebInspector.DOMNode} */
+    this._node = null;
+    this._layerId = String(payload.layer_id);
+    this._offsetX = payload.position[0];
+    this._offsetY = payload.position[1];
+    this._width = payload.bounds.width;
+    this._height = payload.bounds.height;
+    this._children = [];
+    this._parentLayerId = null;
+    this._parent = null;
+    this._quad = payload.layer_quad || [];
+    this._createScrollRects(payload);
+    this._compositingReasons = payload.compositing_reasons || [];
+    this._drawsContent = !!payload.draws_content;
+    this._gpuMemoryUsage = payload.gpu_memory_usage;
+    this._paints = [];
+  }
+
+  /**
+   * @override
+   * @return {string}
+   */
+  id() {
+    return this._layerId;
+  }
+
+  /**
+   * @override
+   * @return {?string}
+   */
+  parentId() {
+    return this._parentLayerId;
+  }
+
+  /**
+   * @override
+   * @return {?WebInspector.Layer}
+   */
+  parent() {
+    return this._parent;
+  }
+
+  /**
+   * @override
+   * @return {boolean}
+   */
+  isRoot() {
+    return !this.parentId();
+  }
+
+  /**
+   * @override
+   * @return {!Array.<!WebInspector.Layer>}
+   */
+  children() {
+    return this._children;
+  }
+
+  /**
+   * @override
+   * @param {!WebInspector.Layer} child
+   */
+  addChild(child) {
+    if (child._parent)
+      console.assert(false, 'Child already has a parent');
+    this._children.push(child);
+    child._parent = this;
+    child._parentLayerId = this._layerId;
+  }
+
+  /**
+   * @param {?WebInspector.DOMNode} node
+   */
+  _setNode(node) {
+    this._node = node;
+  }
+
+  /**
+   * @override
+   * @return {?WebInspector.DOMNode}
+   */
+  node() {
+    return this._node;
+  }
+
+  /**
+   * @override
+   * @return {?WebInspector.DOMNode}
+   */
+  nodeForSelfOrAncestor() {
+    for (var layer = this; layer; layer = layer._parent) {
+      if (layer._node)
+        return layer._node;
+    }
+    return null;
+  }
+
+  /**
+   * @override
+   * @return {number}
+   */
+  offsetX() {
+    return this._offsetX;
+  }
+
+  /**
+   * @override
+   * @return {number}
+   */
+  offsetY() {
+    return this._offsetY;
+  }
+
+  /**
+   * @override
+   * @return {number}
+   */
+  width() {
+    return this._width;
+  }
+
+  /**
+   * @override
+   * @return {number}
+   */
+  height() {
+    return this._height;
+  }
+
+  /**
+   * @override
+   * @return {?Array.<number>}
+   */
+  transform() {
+    return null;
+  }
+
+  /**
+   * @override
+   * @return {!Array.<number>}
+   */
+  quad() {
+    return this._quad;
+  }
+
+  /**
+   * @override
+   * @return {!Array.<number>}
+   */
+  anchorPoint() {
+    return [0.5, 0.5, 0];
+  }
+
+  /**
+   * @override
+   * @return {boolean}
+   */
+  invisible() {
+    return false;
+  }
+
+  /**
+   * @override
+   * @return {number}
+   */
+  paintCount() {
+    return 0;
+  }
+
+  /**
+   * @override
+   * @return {?DOMAgent.Rect}
+   */
+  lastPaintRect() {
+    return null;
+  }
+
+  /**
+   * @override
+   * @return {!Array.<!LayerTreeAgent.ScrollRect>}
+   */
+  scrollRects() {
+    return this._scrollRects;
+  }
+
+  /**
+   * @override
+   * @return {number}
+   */
+  gpuMemoryUsage() {
+    return this._gpuMemoryUsage;
+  }
+
+  /**
+   * @override
+   * @return {!Array<!Promise<?WebInspector.SnapshotWithRect>>}
+   */
+  snapshots() {
+    return this._paints.map(paint => paint.snapshotPromise().then(snapshot => {
+      if (!snapshot)
         return null;
-    },
-
-    /**
-     * @override
-     * @return {number}
-     */
-    offsetX: function()
-    {
-        return this._offsetX;
-    },
-
-    /**
-     * @override
-     * @return {number}
-     */
-    offsetY: function()
-    {
-        return this._offsetY;
-    },
-
-    /**
-     * @override
-     * @return {number}
-     */
-    width: function()
-    {
-        return this._width;
-    },
-
-    /**
-     * @override
-     * @return {number}
-     */
-    height: function()
-    {
-        return this._height;
-    },
-
-    /**
-     * @override
-     * @return {?Array.<number>}
-     */
-    transform: function()
-    {
+      var rect = {x: snapshot.rect[0], y: snapshot.rect[1], width: snapshot.rect[2], height: snapshot.rect[3]};
+      return {rect: rect, snapshot: snapshot.snapshot};
+    }));
+  }
+
+  /**
+   * @param {!Array<number>} targetRect
+   * @return {!Promise<?WebInspector.SnapshotWithRect>}
+   */
+  _pictureForRect(targetRect) {
+    return Promise.all(this._paints.map(paint => paint.picturePromise())).then(pictures => {
+      var fragments =
+          pictures.filter(picture => picture && rectsOverlap(picture.rect, targetRect))
+              .map(picture => ({x: picture.rect[0], y: picture.rect[1], picture: picture.serializedPicture}));
+      if (!fragments.length || !this._target)
         return null;
-    },
-
-    /**
-     * @override
-     * @return {!Array.<number>}
-     */
-    quad: function()
-    {
-        return this._quad;
-    },
-
-    /**
-     * @override
-     * @return {!Array.<number>}
-     */
-    anchorPoint: function()
-    {
-        return [0.5, 0.5, 0];
-    },
-
-    /**
-     * @override
+      var x0 = fragments.reduce((min, item) => Math.min(min, item.x), Infinity);
+      var y0 = fragments.reduce((min, item) => Math.min(min, item.y), Infinity);
+      // Rect is in layer content coordinates, make it relative to picture by offsetting to the top left corner.
+      var rect = {x: targetRect[0] - x0, y: targetRect[1] - y0, width: targetRect[2], height: targetRect[3]};
+      return WebInspector.PaintProfilerSnapshot.loadFromFragments(this._target, fragments)
+          .then(snapshot => snapshot ? {rect: rect, snapshot: snapshot} : null);
+    });
+
+    /**
+     * @param {number} a1
+     * @param {number} a2
+     * @param {number} b1
+     * @param {number} b2
      * @return {boolean}
      */
-    invisible: function()
-    {
-        return false;
-    },
-
-    /**
-     * @override
-     * @return {number}
-     */
-    paintCount: function()
-    {
-        return 0;
-    },
-
-    /**
-     * @override
-     * @return {?DOMAgent.Rect}
-     */
-    lastPaintRect: function()
-    {
-        return null;
-    },
-
-    /**
-     * @override
-     * @return {!Array.<!LayerTreeAgent.ScrollRect>}
-     */
-    scrollRects: function()
-    {
-        return this._scrollRects;
-    },
-
-    /**
-     * @override
-     * @return {number}
-     */
-    gpuMemoryUsage: function()
-    {
-        return this._gpuMemoryUsage;
-    },
-
-    /**
-     * @override
-     * @return {!Array<!Promise<?WebInspector.SnapshotWithRect>>}
-     */
-    snapshots: function()
-    {
-        return this._paints.map(paint => paint.snapshotPromise().then(snapshot => {
-            if (!snapshot)
-                return null;
-            var rect = {x: snapshot.rect[0], y: snapshot.rect[1], width: snapshot.rect[2], height: snapshot.rect[3]};
-            return {rect: rect, snapshot: snapshot.snapshot};
-        }));
-    },
-
-    /**
-     * @param {!Array<number>} targetRect
-     * @return {!Promise<?WebInspector.SnapshotWithRect>}
-     */
-    _pictureForRect: function(targetRect)
-    {
-        return Promise.all(this._paints.map(paint => paint.picturePromise())).then(pictures => {
-            var fragments = pictures.filter(picture => picture && rectsOverlap(picture.rect, targetRect))
-                .map(picture => ({x: picture.rect[0], y: picture.rect[1], picture: picture.serializedPicture}));
-            if (!fragments.length || !this._target)
-                return null;
-            var x0 = fragments.reduce((min, item) => Math.min(min, item.x), Infinity);
-            var y0 = fragments.reduce((min, item) => Math.min(min, item.y), Infinity);
-            // Rect is in layer content coordinates, make it relative to picture by offsetting to the top left corner.
-            var rect = {x: targetRect[0] - x0, y: targetRect[1] - y0, width: targetRect[2], height: targetRect[3]};
-            return WebInspector.PaintProfilerSnapshot.loadFromFragments(this._target, fragments).then(snapshot => snapshot ? {rect: rect, snapshot: snapshot} : null);
-        });
-
-        /**
-         * @param {number} a1
-         * @param {number} a2
-         * @param {number} b1
-         * @param {number} b2
-         * @return {boolean}
-         */
-        function segmentsOverlap(a1, a2, b1, b2)
-        {
-            console.assert(a1 <= a2 && b1 <= b2, "segments should be specified as ordered pairs");
-            return a2 > b1 && a1 < b2;
-        }
-
-        /**
-         * @param {!Array.<number>} a
-         * @param {!Array.<number>} b
-         * @return {boolean}
-         */
-        function rectsOverlap(a, b)
-        {
-            return segmentsOverlap(a[0], a[0] + a[2], b[0], b[0] + b[2]) && segmentsOverlap(a[1], a[1] + a[3], b[1], b[1] + b[3]);
-        }
-    },
-
-    /**
-     * @param {!Array.<number>} params
-     * @param {string} type
-     * @return {!Object}
-     */
-    _scrollRectsFromParams: function(params, type)
-    {
-        return {rect: {x: params[0], y: params[1], width: params[2], height: params[3]}, type: type};
-    },
-
-    /**
-     * @param {!WebInspector.TracingLayerPayload} payload
-     */
-    _createScrollRects: function(payload)
-    {
-        this._scrollRects = [];
-        if (payload.non_fast_scrollable_region)
-            this._scrollRects.push(this._scrollRectsFromParams(payload.non_fast_scrollable_region, WebInspector.Layer.ScrollRectType.NonFastScrollable.name));
-        if (payload.touch_event_handler_region)
-            this._scrollRects.push(this._scrollRectsFromParams(payload.touch_event_handler_region, WebInspector.Layer.ScrollRectType.TouchEventHandler.name));
-        if (payload.wheel_event_handler_region)
-            this._scrollRects.push(this._scrollRectsFromParams(payload.wheel_event_handler_region, WebInspector.Layer.ScrollRectType.WheelEventHandler.name));
-        if (payload.scroll_event_handler_region)
-            this._scrollRects.push(this._scrollRectsFromParams(payload.scroll_event_handler_region, WebInspector.Layer.ScrollRectType.RepaintsOnScroll.name));
-    },
-
-    /**
-     * @param {!WebInspector.LayerPaintEvent} paint
-     */
-    _addPaintEvent: function(paint)
-    {
-        this._paints.push(paint);
-    },
-
-    /**
-     * @override
-     * @param {function(!Array.<string>)} callback
-     */
-    requestCompositingReasons: function(callback)
-    {
-        callback(this._compositingReasons);
-    },
+    function segmentsOverlap(a1, a2, b1, b2) {
+      console.assert(a1 <= a2 && b1 <= b2, 'segments should be specified as ordered pairs');
+      return a2 > b1 && a1 < b2;
+    }
 
     /**
-     * @override
+     * @param {!Array.<number>} a
+     * @param {!Array.<number>} b
      * @return {boolean}
      */
-    drawsContent: function()
-    {
-        return this._drawsContent;
+    function rectsOverlap(a, b) {
+      return segmentsOverlap(a[0], a[0] + a[2], b[0], b[0] + b[2]) &&
+          segmentsOverlap(a[1], a[1] + a[3], b[1], b[1] + b[3]);
     }
+  }
+
+  /**
+   * @param {!Array.<number>} params
+   * @param {string} type
+   * @return {!Object}
+   */
+  _scrollRectsFromParams(params, type) {
+    return {rect: {x: params[0], y: params[1], width: params[2], height: params[3]}, type: type};
+  }
+
+  /**
+   * @param {!WebInspector.TracingLayerPayload} payload
+   */
+  _createScrollRects(payload) {
+    this._scrollRects = [];
+    if (payload.non_fast_scrollable_region)
+      this._scrollRects.push(this._scrollRectsFromParams(
+          payload.non_fast_scrollable_region, WebInspector.Layer.ScrollRectType.NonFastScrollable.name));
+    if (payload.touch_event_handler_region)
+      this._scrollRects.push(this._scrollRectsFromParams(
+          payload.touch_event_handler_region, WebInspector.Layer.ScrollRectType.TouchEventHandler.name));
+    if (payload.wheel_event_handler_region)
+      this._scrollRects.push(this._scrollRectsFromParams(
+          payload.wheel_event_handler_region, WebInspector.Layer.ScrollRectType.WheelEventHandler.name));
+    if (payload.scroll_event_handler_region)
+      this._scrollRects.push(this._scrollRectsFromParams(
+          payload.scroll_event_handler_region, WebInspector.Layer.ScrollRectType.RepaintsOnScroll.name));
+  }
+
+  /**
+   * @param {!WebInspector.LayerPaintEvent} paint
+   */
+  _addPaintEvent(paint) {
+    this._paints.push(paint);
+  }
+
+  /**
+   * @override
+   * @param {function(!Array.<string>)} callback
+   */
+  requestCompositingReasons(callback) {
+    callback(this._compositingReasons);
+  }
+
+  /**
+   * @override
+   * @return {boolean}
+   */
+  drawsContent() {
+    return this._drawsContent;
+  }
 };