[Media Router] Support dual discovery

chrome/browser/media/router/discovery/dial/dial_media_sink_service_proxy.h

Index: chrome/browser/media/router/discovery/dial/dial_media_sink_service_proxy.h
diff --git a/chrome/browser/media/router/discovery/dial/dial_media_sink_service_proxy.h b/chrome/browser/media/router/discovery/dial/dial_media_sink_service_proxy.h
index b11bad149255a7ddd472059cb840281f16c48cdf..2a1e4c8212c73ed5bc907f4095ad4dabd7dbdfec 100644
--- a/chrome/browser/media/router/discovery/dial/dial_media_sink_service_proxy.h
+++ b/chrome/browser/media/router/discovery/dial/dial_media_sink_service_proxy.h
@@ -50,6 +50,10 @@ class DialMediaSinkServiceProxy
   // Start() is cleared.
   void Stop() override;
 
+  // MediaSinkService implementation.
+  void AddObserver(Observer* observer) override;
+  void RemoveObserver(Observer* observer) override;
+
   void SetDialMediaSinkServiceForTest(
       std::unique_ptr<DialMediaSinkServiceImpl> dial_media_sink_service);
 
@@ -77,6 +81,8 @@ class DialMediaSinkServiceProxy
 
   scoped_refptr<net::URLRequestContextGetter> request_context_;
 
+  Observer* observer_;
+
   DISALLOW_COPY_AND_ASSIGN(DialMediaSinkServiceProxy);
 };