DevTools: use target-based model accessors only.

Source/devtools/front_end/timeline/TimelinePowerOverview.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}
+ * @param {?WebInspector.Target} target
  */
-WebInspector.TimelinePowerOverviewDataProvider = function()
+WebInspector.TimelinePowerOverviewDataProvider = function(target)
 {
     this._records = [];
     this._energies = [];
     this._times = [];
-    WebInspector.powerProfiler.addEventListener(WebInspector.PowerProfiler.EventTypes.PowerEventRecorded, this._onRecordAdded, this);
+    this._target = target;
+    if (this._target)
+        this._target.powerProfiler.addEventListener(WebInspector.PowerProfiler.EventTypes.PowerEventRecorded, this._onRecordAdded, this);
 }
 
 WebInspector.TimelinePowerOverviewDataProvider.prototype = {
     dispose: function()
     {
-        WebInspector.powerProfiler.removeEventListener(WebInspector.PowerProfiler.EventTypes.PowerEventRecorded, this._onRecordAdded, this);
+        if (this._target)
+            this._target.powerProfiler.removeEventListener(WebInspector.PowerProfiler.EventTypes.PowerEventRecorded, this._onRecordAdded, this);
     },
 
     /**
      * @return {!Array.<!PowerAgent.PowerEvent>}
      */
     records : function()
     {
         // The last record is not used, as its "value" is not set.
         return this._records.slice(0, this._records.length - 1);
     },
@@ skipping 55 matching lines @@
 }
 
 /**
  * @constructor
  * @extends {WebInspector.TimelineOverviewBase}
  * @param {!WebInspector.TimelineModel} model
  */
 WebInspector.TimelinePowerOverview = function(model)
 {
     WebInspector.TimelineOverviewBase.call(this, model);
+
+    // FIXME: Figure out optional targets in timeline.
+    this._target = model.target();
     this.element.id = "timeline-overview-power";
-    this._dataProvider = new WebInspector.TimelinePowerOverviewDataProvider();
+    this._dataProvider = new WebInspector.TimelinePowerOverviewDataProvider(this._target);
 
     this._maxPowerLabel = this.element.createChild("div", "max memory-graph-label");
     this._minPowerLabel = this.element.createChild("div", "min memory-graph-label");
 }
 
 WebInspector.TimelinePowerOverview.prototype = {
     /**
      * @override
      */
     dispose: function()
     {
         this._dataProvider.dispose();
     },
 
     timelineStarted: function()
     {
-        if (WebInspector.targetManager.mainTarget().hasCapability(WebInspector.Target.Capabilities.CanProfilePower))
-            WebInspector.powerProfiler.startProfile();
+        if (this._target && this._target.hasCapability(WebInspector.Target.Capabilities.CanProfilePower))
+            this._target.powerProfiler.startProfile();
     },
 
     timelineStopped: function()
     {
-        if (WebInspector.targetManager.mainTarget().hasCapability(WebInspector.Target.Capabilities.CanProfilePower))
-            WebInspector.powerProfiler.stopProfile();
+        if (this._target && this._target.hasCapability(WebInspector.Target.Capabilities.CanProfilePower))
+            this._target.powerProfiler.stopProfile();
     },
 
     _resetPowerLabels: function()
     {
         this._maxPowerLabel.textContent = "";
         this._minPowerLabel.textContent = "";
     },
 
     /**
      * @override
@@ skipping 78 matching lines @@
     /**
      * @param {number} minTime
      * @param {number} maxTime
      * @return {number} energy in joules.
      */
     calculateEnergy: function(minTime, maxTime)
     {
         return this._dataProvider._calculateEnergy(minTime, maxTime);
     },
 
+    /**
+     * @return {string}
+     */
+    accuracyLevel: function()
+    {
+        return this._target ? this._target.powerProfiler.accuracyLevel() : "";
+    },
+
     __proto__: WebInspector.TimelineOverviewBase.prototype
 }