[MediaRouter] Record DIAL device counts in DialMediaSinkServiceImpl

chrome/browser/media/router/discovery/media_sink_service_base.h

 // Copyright 2017 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_MEDIA_ROUTER_DISCOVERY_MEDIA_SINK_SERVICE_BASE_H_
 #define CHROME_BROWSER_MEDIA_ROUTER_DISCOVERY_MEDIA_SINK_SERVICE_BASE_H_
 
 #include <memory>
 #include <set>
 
@@ skipping 19 matching lines @@
   // exists.
   void StartTimer();
 
   // Helper function to stop |finish_timer_|.
   void StopTimer();
 
   // Helper function to restart |finish_timer|. No-op if timer does not exist or
   // timer is currently running.
   void RestartTimer();
 
+  // Overriden by subclass to report device counts.
+  virtual void RecordDeviceCounts() {}
+
   // Time out value for |finish_timer_|
   int fetch_complete_timeout_secs_;
 
   // Sorted sinks from current round of discovery.
   std::set<MediaSinkInternal> current_sinks_;
 
   // Sorted sinks sent to Media Router Provider in last FetchCompleted().
   std::set<MediaSinkInternal> mrp_sinks_;
 
  private:
   friend class MediaSinkServiceBaseTest;
   FRIEND_TEST_ALL_PREFIXES(MediaSinkServiceBaseTest,
                            TestFetchCompleted_SameSink);
 
   // Timer for finishing fetching.
   std::unique_ptr<base::Timer> finish_timer_;
 };
 
 }  // namespace media_router
 
 #endif  // CHROME_BROWSER_MEDIA_ROUTER_DISCOVERY_MEDIA_SINK_SERVICE_BASE_H_