[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 1de6be4443a7733260bc601434a868c1b1070560..c9ae7e7b76c2c3644abd851cf8520f210ed710a3 100644
--- a/Source/devtools/front_end/Settings.js
+++ b/Source/devtools/front_end/Settings.js
@@ -39,6 +39,7 @@ var Preferences = {
 
 var Capabilities = {
     isMainFrontend: false,
+    canProfilePower: false,
 }
 
 /**
@@ -289,6 +290,7 @@ WebInspector.ExperimentsSettings = function(experimentsEnabled)
     this.heapSnapshotStatistics = this._createExperiment("heapSnapshotStatistics", "Show memory breakdown statistics in heap snapshots");
     this.timelineNoLiveUpdate = this._createExperiment("timelineNoLiveUpdate", "Timeline w/o live update");
     this.cssStyleSearch = this._createExperiment("cssStyleSearch", "Enable Styles search and Computed style filtering");
+    this.powerProfiler = this._createExperiment("powerProfiler", "Enable power mode in Timeline");
 
     this._cleanUpSetting();
 }