DevTools: add Tracing agent on back-end

Source/devtools/front_end/TimelineManager.js

 /*
  * Copyright (C) 2011 Google Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are
  * met:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
  *     * Redistributions in binary form must reproduce the above
@@ skipping 20 matching lines @@
 /**
  * @constructor
  * @extends {WebInspector.TargetAwareObject}
  * @param {!WebInspector.Target} target
  */
 WebInspector.TimelineManager = function(target)
 {
     WebInspector.TargetAwareObject.call(this, target);
     this._dispatcher = new WebInspector.TimelineDispatcher(this);
     this._enablementCount = 0;
-    TimelineAgent.enable(WebInspector.experimentsSettings.timelineTracingMode.isEnabled() ? WebInspector.TimelineManager.defaultTracingCategories : "");
+    TimelineAgent.enable();
 }
 
 WebInspector.TimelineManager.EventTypes = {
     TimelineStarted: "TimelineStarted",
     TimelineStopped: "TimelineStopped",
     TimelineEventRecorded: "TimelineEventRecorded",
     TimelineProgress: "TimelineProgress"
 }
 
-WebInspector.TimelineManager.defaultTracingCategories = "*,disabled-by-default-cc.debug,disabled-by-default-devtools.timeline";
-
 WebInspector.TimelineManager.prototype = {
     /**
      * @return {boolean}
      */
     isStarted: function()
     {
         return this._dispatcher.isStarted();
     },
 
     /**
@@ skipping 147 matching lines @@
     progress: function(count)
     {
         this._manager.dispatchEventToListeners(WebInspector.TimelineManager.EventTypes.TimelineProgress, count);
     }
 }
 
 /**
  * @type {!WebInspector.TimelineManager}
  */
 WebInspector.timelineManager;