[Media Router] Support dual discovery

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

Index: chrome/browser/media/router/discovery/dial/dial_media_sink_service_proxy.cc
diff --git a/chrome/browser/media/router/discovery/dial/dial_media_sink_service_proxy.cc b/chrome/browser/media/router/discovery/dial/dial_media_sink_service_proxy.cc
index 10801e62a22990df9f86b6cd014d01a1e0c52461..a8e00a70d0e7b49dad5f2b805303071ed8a4c40c 100644
--- a/chrome/browser/media/router/discovery/dial/dial_media_sink_service_proxy.cc
+++ b/chrome/browser/media/router/discovery/dial/dial_media_sink_service_proxy.cc
@@ -14,7 +14,7 @@ namespace media_router {
 DialMediaSinkServiceProxy::DialMediaSinkServiceProxy(
     const MediaSinkService::OnSinksDiscoveredCallback& callback,
     content::BrowserContext* context)
-    : MediaSinkService(callback) {
+    : MediaSinkService(callback), observer_(nullptr) {
   DCHECK_CURRENTLY_ON(BrowserThread::UI);
   auto* profile = Profile::FromBrowserContext(context);
   request_context_ = profile->GetRequestContext();
@@ -39,6 +39,21 @@ void DialMediaSinkServiceProxy::Stop() {
       base::Bind(&DialMediaSinkServiceProxy::StopOnIOThread, this));
 }
 
+void DialMediaSinkServiceProxy::AddObserver(Observer* observer) {
+  DCHECK_CURRENTLY_ON(BrowserThread::UI);
+  DCHECK(observer);
+  observer_ = observer;
+}
+
+void DialMediaSinkServiceProxy::RemoveObserver(Observer* observer) {
+  DCHECK_CURRENTLY_ON(BrowserThread::UI);
+  DCHECK(observer);
+  if (dial_media_sink_service_)
+    dial_media_sink_service_->RemoveObserver(observer);
+
+  observer_ = nullptr;
+}
+
 void DialMediaSinkServiceProxy::SetDialMediaSinkServiceForTest(
     std::unique_ptr<DialMediaSinkServiceImpl> dial_media_sink_service) {
   DCHECK(dial_media_sink_service);
@@ -54,6 +69,8 @@ void DialMediaSinkServiceProxy::StartOnIOThread() {
         base::Bind(&DialMediaSinkServiceProxy::OnSinksDiscoveredOnIOThread,
                    this),
         request_context_.get());
+    if (observer_)
+      dial_media_sink_service_->AddObserver(observer_);
   }
 
   dial_media_sink_service_->Start();