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

Source/devtools/front_end/Settings.js

Index: Source/devtools/front_end/Settings.js
diff --git a/Source/devtools/front_end/Settings.js b/Source/devtools/front_end/Settings.js
index 54c8c21bde123ed67d9b44eec6616d56b633672e..e5ef01327f6fc80d52806701d1198fd7125b0682 100644
--- a/Source/devtools/front_end/Settings.js
+++ b/Source/devtools/front_end/Settings.js
@@ -40,6 +40,7 @@ var Preferences = {
 
 var Capabilities = {
     canInspectWorkers: false,
+    canProfilePower: false,
 }
 
 /**
@@ -288,6 +289,7 @@ WebInspector.ExperimentsSettings = function()
     this.allocationProfiler = this._createExperiment("allocationProfiler", "Enable JavaScript heap allocation profiler");
     this.timelineFlameChart = this._createExperiment("timelineFlameChart", "Enable FlameChart mode in Timeline");
     this.heapSnapshotStatistics = this._createExperiment("heapSnapshotStatistics", "Show memory breakdown statistics in heap snapshots");
+    this.powerProfiler = this._createExperiment("powerProfiler", "Enable power mode in Timeline");
 
     this._cleanUpSetting();
 }