[Media Router] Add UMA metrics for Media Router Dialog WebUI performance.

chrome/browser/ui/webui/media_router/media_router_ui.h

 // Copyright 2015 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.
 
 #ifndef CHROME_BROWSER_UI_WEBUI_MEDIA_ROUTER_MEDIA_ROUTER_UI_H_
 #define CHROME_BROWSER_UI_WEBUI_MEDIA_ROUTER_MEDIA_ROUTER_UI_H_
 
 #include <set>
 #include <string>
 #include <vector>
@@ skipping 103 matching lines @@
     return current_route_request_id_ != -1;
   }
   const std::vector<MediaSinkWithCastModes>& sinks() const { return sinks_; }
   const std::vector<MediaRoute>& routes() const { return routes_; }
   const std::set<MediaCastMode>& cast_modes() const { return cast_modes_; }
   const content::WebContents* initiator() const { return initiator_; }
 
   // Marked virtual for tests.
   virtual const std::string& GetRouteProviderExtensionId() const;
 
+  // Called to track UI metrics.
+  void SetUIInitializationTimer(const base::Time& start_time);
+  void OnUIInitiallyLoaded();
+  void OnUIInitialDataReceived();
+
  private:
   FRIEND_TEST_ALL_PREFIXES(MediaRouterUITest,
                            UIMediaRoutesObserverFiltersNonDisplayRoutes);
   FRIEND_TEST_ALL_PREFIXES(MediaRouterUITest, GetExtensionNameExtensionPresent);
   FRIEND_TEST_ALL_PREFIXES(MediaRouterUITest,
                            GetExtensionNameEmptyWhenNotInstalled);
   FRIEND_TEST_ALL_PREFIXES(MediaRouterUITest,
                            GetExtensionNameEmptyWhenNotExtensionURL);
 
   class UIIssuesObserver;
@@ skipping 102 matching lines @@
   base::WeakPtr<PresentationServiceDelegateImpl> presentation_service_delegate_;
 
   content::WebContents* initiator_;
 
   // Pointer to the MediaRouter for this instance's BrowserContext.
   MediaRouterMojoImpl* router_;
 
   // Timer used to implement a timeout on a create route request.
   base::OneShotTimer route_creation_timer_;
 
+  // The start time for UI initialization metrics timer. When a dialog has been
+  // been painted and initialized with initial data, this should be cleared.
+  base::Time start_time_;
+
   // NOTE: Weak pointers must be invalidated before all other member variables.
   // Therefore |weak_factory_| must be placed at the end.
   base::WeakPtrFactory<MediaRouterUI> weak_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(MediaRouterUI);
 };
 
 }  // namespace media_router
 
 #endif  // CHROME_BROWSER_UI_WEBUI_MEDIA_ROUTER_MEDIA_ROUTER_UI_H_