[Media Router] Support dual discovery

chrome/browser/media/router/discovery/dial/dial_media_sink_service_proxy.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_DIAL_DIAL_MEDIA_SINK_SERVICE_PROXY_H_
 #define CHROME_BROWSER_MEDIA_ROUTER_DISCOVERY_DIAL_DIAL_MEDIA_SINK_SERVICE_PROXY_H_
 
 #include <memory>
 
 #include "base/macros.h"
@@ skipping 32 matching lines @@
       content::BrowserContext* context);
 
   // Starts discovery of DIAL devices on IO thread. Caller is responsible for
   // calling Stop() before destroying this object..
   void Start() override;
 
   // Stops discovery of DIAL devices on IO thread. The callback passed to
   // 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);
 
  private:
   friend class DialMediaSinkServiceProxyTest;
   friend class base::DeleteHelper<DialMediaSinkServiceProxy>;
   friend struct content::BrowserThread::DeleteOnThread<
       content::BrowserThread::IO>;
   friend class base::RefCountedThreadSafe<DialMediaSinkServiceProxy>;
 
   ~DialMediaSinkServiceProxy() override;
 
   // Starts DIAL discovery.
   void StartOnIOThread();
 
   // Stops DIAL discovery.
   void StopOnIOThread();
 
   // Callback passed to |dial_media_sink_service_| ctor. When invoked, post task
   // to UI thread and invoke |sink_discovery_callback_|.
   void OnSinksDiscoveredOnIOThread(std::vector<MediaSinkInternal> sinks);
 
  private:
   std::unique_ptr<DialMediaSinkServiceImpl> dial_media_sink_service_;
 
   scoped_refptr<net::URLRequestContextGetter> request_context_;
 
+  Observer* observer_;
+
   DISALLOW_COPY_AND_ASSIGN(DialMediaSinkServiceProxy);
 };
 
 }  // namespace media_router
 
 #endif  // CHROME_BROWSER_MEDIA_ROUTER_DISCOVERY_DIAL_DIAL_MEDIA_SINK_SERVICE_PROXY_H_