[Media Router] Use DialMediaSinkService in MediaRouterMojoImpl

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

Index: chrome/browser/media/router/discovery/dial/dial_media_sink_service_impl.cc
diff --git a/chrome/browser/media/router/discovery/dial/dial_media_sink_service_impl.cc b/chrome/browser/media/router/discovery/dial/dial_media_sink_service_impl.cc
index 73551d9cb89211ab8d6db2718cc0951f8391292b..fde508f6cd901134c52eb20d99a9658c04e3e58c 100644
--- a/chrome/browser/media/router/discovery/dial/dial_media_sink_service_impl.cc
+++ b/chrome/browser/media/router/discovery/dial/dial_media_sink_service_impl.cc
@@ -34,6 +34,7 @@ void DialMediaSinkServiceImpl::Start() {
   dial_registry_ = DialRegistry::GetInstance();
   dial_registry_->RegisterObserver(this);
   dial_registry_->OnListenerAdded();
+  StartTimer();
 }
 
 void DialMediaSinkServiceImpl::Stop() {
@@ -44,6 +45,7 @@ void DialMediaSinkServiceImpl::Stop() {
   dial_registry_->OnListenerRemoved();
   dial_registry_->UnregisterObserver(this);
   dial_registry_ = nullptr;
+  finish_timer_.reset();
 }
 
 DeviceDescriptionService* DialMediaSinkServiceImpl::GetDescriptionService() {
@@ -80,11 +82,6 @@ void DialMediaSinkServiceImpl::OnDialDeviceEvent(
   DVLOG(2) << "DialMediaSinkServiceImpl::OnDialDeviceEvent found "
            << devices.size() << " devices";
 
-  // Timer starts in |OnDialDeviceEvent()|, and expires 3 seconds later. If
-  // |OnDeviceDescriptionAvailable()| is called after |finish_timer_| expires,
-  // |finish_timer_| is restarted.
-  StartTimer();
-
   current_sinks_.clear();
   current_devices_ = devices;