[Media Router] Add P1 UMA metrics for Media Router.

chrome/browser/ui/toolbar/media_router_action_platform_delegate.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_TOOLBAR_MEDIA_ROUTER_ACTION_PLATFORM_DELEGATE_H_
 #define CHROME_BROWSER_UI_TOOLBAR_MEDIA_ROUTER_ACTION_PLATFORM_DELEGATE_H_
 
 #include "base/memory/scoped_ptr.h"
 
 class Browser;
 
 class MediaRouterActionPlatformDelegate {
  public:
   MediaRouterActionPlatformDelegate() {}
   virtual ~MediaRouterActionPlatformDelegate() {}
 
   // Returns a created MediaRouterActionPlatformDelegate. This is defined in the
   // platform-specific implementation for the class.
   static scoped_ptr<MediaRouterActionPlatformDelegate> Create(Browser* browser);
 
-  // Closes the overflow menu, if it was open.
-  virtual void CloseOverflowMenuIfOpen() = 0;
+  // Closes the overflow menu, if it was open. Returns whether or not the
+  // overflow menu was closed.
+  virtual bool CloseOverflowMenuIfOpen() = 0;
 };
 
 #endif  // CHROME_BROWSER_UI_TOOLBAR_MEDIA_ROUTER_ACTION_PLATFORM_DELEGATE_H_