[Media Router] Support dual discovery

chrome/browser/media/router/discovery/dial/dial_media_sink_service_impl.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_IMPL_H_
 #define CHROME_BROWSER_MEDIA_ROUTER_DISCOVERY_DIAL_DIAL_MEDIA_SINK_SERVICE_IMPL_H_
 
 #include <memory>
 #include <set>
 
 #include "chrome/browser/media/router/discovery/dial/device_description_service.h"
 #include "chrome/browser/media/router/discovery/dial/dial_registry.h"
 #include "chrome/browser/media/router/discovery/media_sink_service_base.h"
 #include "chrome/browser/media/router/media_router_metrics.h"
 
 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.
 class DialMediaSinkServiceImpl : public MediaSinkServiceBase,
                                  public DialRegistry::Observer {
  public:
   DialMediaSinkServiceImpl(const OnSinksDiscoveredCallback& callback,
                            net::URLRequestContextGetter* request_context);
   ~DialMediaSinkServiceImpl() override;
 
+  void SetDialMediaSinkServiceDelegate(
+      scoped_refptr<DialMediaSinkServiceDelegate> delegate);
+
   // MediaSinkService implementation
   void Start() override;
   void Stop() override;
 
  protected:
   // Returns instance of device description service. Create a new one if none
   // exists.
   DeviceDescriptionService* GetDescriptionService();
 
   // Does not take ownership of |dial_registry|.
@@ skipping 30 matching lines @@
 
   // Raw pointer to DialRegistry singleton.
   DialRegistry* dial_registry_ = nullptr;
 
   // DialRegistry for unit test.
   DialRegistry* test_dial_registry_ = nullptr;
 
   // Device data list from current round of discovery.
   DialRegistry::DeviceList current_devices_;
 
+  scoped_refptr<DialMediaSinkServiceDelegate> delegate_;
+
   scoped_refptr<net::URLRequestContextGetter> request_context_;
 
   MediaRouterMetrics metrics_;
 };
 
 }  // namespace media_router
 
 #endif  // CHROME_BROWSER_MEDIA_ROUTER_DISCOVERY_DIAL_DIAL_MEDIA_SINK_SERVICE_IMPL_H_