Support counter graphs in Timeline based on trace events

Source/devtools/front_end/timeline/TracingTimelineModel.js

 // Copyright 2014 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.
 
 /**
  * @param {!WebInspector.TracingModel} tracingModel
  * @constructor
  * @extends {WebInspector.TimelineModel}
  */
 WebInspector.TracingTimelineModel = function(tracingModel)
@@ skipping 589 matching lines @@
      * @return {string}
      */
     type: function()
     {
         return this._event.name;
     },
 
     /**
      * @return {?Object}
      */
+    counters: function()
+    {
+        return this.type() === WebInspector.TracingTimelineModel.RecordType.UpdateCounters ? this._event.args.data : null;
+    },
+
+    /**
+     * @return {?Object}
+     */
     highlightQuad: function()
     {
         return this._event.highlightQuad || null;
     },
 
     /**
      * @return {string}
      */
     frameId: function()
     {
@@ skipping 66 matching lines @@
     {
         var tokens = [this.title()];
         var data = this._event.args.data;
         if (data) {
             for (var key in data)
                 tokens.push(data[key]);
         }
         return regExp.test(tokens.join("|"));
     }
 }