[DevTools] Add power profiler and power overview in timeline panel.

Source/devtools/front_end/PowerProfiler.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.
+
+/**
+ * @constructor
+ * @extends {WebInspector.Object}
+ */
+WebInspector.PowerProfiler = function()
+{
+    WebInspector.Object.call(this);
+    this._dispatcher = new WebInspector.PowerDispatcher(this);
+}
+
+WebInspector.PowerProfiler.EventTypes = {
+    PowerEventRecorded: "PowerEventRecorded"
+}
+
+WebInspector.PowerProfiler.prototype = {
+
+    startProfile: function ()
+    {
+        PowerAgent.start();
+    },
+
+    stopProfile: function ()
+    {
+        PowerAgent.end();
+    },
+
+    __proto__: WebInspector.Object.prototype
+}
+
+/**
+ * @constructor
+ * @implements {WebInspector.PowerEventDispatcher}
+ */
+WebInspector.PowerDispatcher = function(profiler)
+{
+    this._profiler = profiler;
+    InspectorBackend.registerPowerDispatcher(this);
+}
+
+WebInspector.PowerDispatcher.prototype = {
+    dataAvailable: function(events)
+    {
+        for (var i in events) {
+            events[i]["startTime"] = events[i].timestamp;
+            delete events[i].timestamp;
+            this._profiler.dispatchEventToListeners(WebInspector.PowerProfiler.EventTypes.PowerEventRecorded, events[i]);

[pfeldman, 2014/03/11 12:24:02]

It is better to repack data here instead of renaming timestamp to startTime.
I.e. start with a brand new object of a new type and copy the properties you
need. Or use the original payload type (It has a type {ProwerAgent.PowerEvent}).
But not something in the middle.

[Pan, 2014/03/18 10:16:48]

Done.

+        }
+    }
+}
+
+/**
+ * @type {!WebInspector.PowerProfiler}
+ */
+WebInspector.powerProfiler;