[Media Router] Support dual discovery

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

Index: chrome/browser/media/router/discovery/dial/dial_media_sink_service_impl.h
diff --git a/chrome/browser/media/router/discovery/dial/dial_media_sink_service_impl.h b/chrome/browser/media/router/discovery/dial/dial_media_sink_service_impl.h
index e238bc4ed7de4679807f3c1ba538b5642fea9592..4209d199c45162665f55c783516dc515e24b3e89 100644
--- a/chrome/browser/media/router/discovery/dial/dial_media_sink_service_impl.h
+++ b/chrome/browser/media/router/discovery/dial/dial_media_sink_service_impl.h
@@ -18,6 +18,24 @@ namespace media_router {
 class DeviceDescriptionService;
 class DialRegistry;
 
+// A delegate class registered with DialMediaSinkService to receive
+// notifications when dial sinks are added or removed from DialMediaSinkService
+class DialMediaSinkServiceDelegate
+    : public base::RefCountedThreadSafe<DialMediaSinkServiceDelegate> {
+ public:
+  // Invoked when |sink| is added to DialMediaSinkServiceImpl instance.
+  virtual void OnDialSinkAdded(const MediaSinkInternal& sink) = 0;
+
+  // Invoked when dial sinks are removed from DialMediaSinkServiceImpl instance.
+  virtual void OnDialSinksRemoved() = 0;
+
+ protected:
+  virtual ~DialMediaSinkServiceDelegate() {}
+
+ private:
+  friend class base::RefCountedThreadSafe<DialMediaSinkServiceDelegate>;
+};
+
 // A service which can be used to start background discovery and resolution of
 // DIAL devices (Smart TVs, Game Consoles, etc.).
 // This class is not thread safe. All methods must be called from the IO thread.
@@ -28,6 +46,9 @@ class DialMediaSinkServiceImpl : public MediaSinkServiceBase,
                            net::URLRequestContextGetter* request_context);
   ~DialMediaSinkServiceImpl() override;
 
+  void SetDialMediaSinkServiceDelegate(
+      scoped_refptr<DialMediaSinkServiceDelegate> delegate);
+
   // MediaSinkService implementation
   void Start() override;
   void Stop() override;
@@ -78,6 +99,8 @@ class DialMediaSinkServiceImpl : public MediaSinkServiceBase,
   // Device data list from current round of discovery.
   DialRegistry::DeviceList current_devices_;
 
+  scoped_refptr<DialMediaSinkServiceDelegate> delegate_;
+
   scoped_refptr<net::URLRequestContextGetter> request_context_;
 
   MediaRouterMetrics metrics_;