[Media Router] Support dual discovery

chrome/browser/media/router/mojo/media_router_mojo_impl.cc

Index: chrome/browser/media/router/mojo/media_router_mojo_impl.cc
diff --git a/chrome/browser/media/router/mojo/media_router_mojo_impl.cc b/chrome/browser/media/router/mojo/media_router_mojo_impl.cc
index 3871ccd6ecabfe972bf4add744833365ccdff41b..11592db63db81e54cd01ea2198993929e8ee12a3 100644
--- a/chrome/browser/media/router/mojo/media_router_mojo_impl.cc
+++ b/chrome/browser/media/router/mojo/media_router_mojo_impl.cc
@@ -81,8 +81,14 @@ MediaRouterMojoImpl::MediaRouterMojoImpl(
 
 MediaRouterMojoImpl::~MediaRouterMojoImpl() {
   DCHECK_CURRENTLY_ON(content::BrowserThread::UI);
-  if (dial_media_sink_service_proxy_)
-    dial_media_sink_service_proxy_->Stop();
+  if (!dial_media_sink_service_proxy_)
+    return;
+  dial_media_sink_service_proxy_->Stop();
+
+  if (!cast_media_sink_service_)
+    return;
+  dial_media_sink_service_proxy_->RemoveObserver(
+      cast_media_sink_service_.get());
 }
 
 // static
@@ -1086,16 +1092,6 @@ void MediaRouterMojoImpl::StartDiscovery() {
   DCHECK_CURRENTLY_ON(content::BrowserThread::UI);
   DVLOG_WITH_INSTANCE(1) << "StartDiscovery";
 
-  if (media_router::DialLocalDiscoveryEnabled()) {
-    if (!dial_media_sink_service_proxy_) {
-      dial_media_sink_service_proxy_ = new DialMediaSinkServiceProxy(
-          base::Bind(&MediaRouterMojoImpl::ProvideSinks,
-                     weak_factory_.GetWeakPtr(), "dial"),
-          context_);
-    }
-    dial_media_sink_service_proxy_->Start();
-  }
-
   if (media_router::CastDiscoveryEnabled()) {
     if (!cast_media_sink_service_) {
       cast_media_sink_service_ = new CastMediaSinkService(
@@ -1105,6 +1101,21 @@ void MediaRouterMojoImpl::StartDiscovery() {
     }
     cast_media_sink_service_->Start();
   }
+
+  if (media_router::DialLocalDiscoveryEnabled()) {
+    if (!dial_media_sink_service_proxy_) {
+      dial_media_sink_service_proxy_ = new DialMediaSinkServiceProxy(
+          base::Bind(&MediaRouterMojoImpl::ProvideSinks,
+                     weak_factory_.GetWeakPtr(), "dial"),
+          context_);
+      // Add observer for dual discovery.
+      if (cast_media_sink_service_) {
+        dial_media_sink_service_proxy_->AddObserver(
+            cast_media_sink_service_.get());
+      }
+    }
+    dial_media_sink_service_proxy_->Start();
+  }
 }
 
 void MediaRouterMojoImpl::UpdateMediaSinks(