[Media Router] Add UMA metrics to record the load time for route controls

chrome/browser/ui/webui/media_router/media_router_webui_message_handler.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_WEBUI_MESSAGE_HANDLER_H_
 #define CHROME_BROWSER_UI_WEBUI_MEDIA_ROUTER_MEDIA_ROUTER_WEBUI_MESSAGE_HANDLER_H_
 
 #include <unordered_map>
 #include <vector>
 
@@ skipping 87 matching lines @@
   void OnReportClickedSinkIndex(const base::ListValue* args);
   void OnReportFilter(const base::ListValue* args);
   void OnReportInitialAction(const base::ListValue* args);
   void OnReportInitialState(const base::ListValue* args);
   void OnReportNavigateToView(const base::ListValue* args);
   void OnReportRouteCreation(const base::ListValue* args);
   void OnReportRouteCreationOutcome(const base::ListValue* args);
   void OnReportSelectedCastMode(const base::ListValue* args);
   void OnReportSinkCount(const base::ListValue* args);
   void OnReportTimeToClickSink(const base::ListValue* args);
+  void OnReportWebUIRouteControllerLoaded(const base::ListValue* args);
   void OnReportTimeToInitialActionClose(const base::ListValue* args);
   void OnMediaControllerAvailable(const base::ListValue* args);
   void OnMediaControllerClosed(const base::ListValue* args);
   void OnSearchSinksAndCreateRoute(const base::ListValue* args);
   void OnInitialDataReceived(const base::ListValue* args);
 
   // Handlers for JavaScript messages to control the media.
   void OnPlayCurrentMedia(const base::ListValue* args);
   void OnPauseCurrentMedia(const base::ListValue* args);
   void OnSeekCurrentMedia(const base::ListValue* args);
@@ skipping 41 matching lines @@
   base::Optional<MediaStatus> current_media_status_;
 
   MediaRouterUI* media_router_ui_;
 
   DISALLOW_COPY_AND_ASSIGN(MediaRouterWebUIMessageHandler);
 };
 
 }  // namespace media_router
 
 #endif  // CHROME_BROWSER_UI_WEBUI_MEDIA_ROUTER_MEDIA_ROUTER_WEBUI_MESSAGE_HANDLER_H_