Add ProcessPowerCollector to audit power information.

apps/app_window.h

Index: apps/app_window.h
diff --git a/apps/app_window.h b/apps/app_window.h
index 4239d010b8923c1152f0d41c3431f4b59bef7d93..77e5436e6e8252047d3040340663d1a72b1a4f67 100644
--- a/apps/app_window.h
+++ b/apps/app_window.h
@@ -347,6 +347,10 @@ class AppWindow : public content::NotificationObserver,
   // Whether the app window wants to be alpha enabled.
   bool requested_alpha_enabled() const { return requested_alpha_enabled_; }
 
+  void SetAppWindowContentsForTesting(scoped_ptr<AppWindowContents> contents) {
+    app_window_contents_ = contents.Pass();
+  }
+
  protected:
   virtual ~AppWindow();