[Media Router] Replace route messaging API.

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 9ba4318b0f292932144f542509f5e351429c539d..9dcfb5f2c2e5e48b7ede48fbc64c64188020d4bc 100644
--- a/chrome/browser/media/router/mojo/media_router_mojo_impl.cc
+++ b/chrome/browser/media/router/mojo/media_router_mojo_impl.cc
@@ -596,8 +596,11 @@ void MediaRouterMojoImpl::RegisterPresentationSessionMessagesObserver(
   bool should_listen = !observer_list->might_have_observers();
   observer_list->AddObserver(observer);
   if (should_listen) {
-    RunOrDefer(base::Bind(&MediaRouterMojoImpl::DoListenForRouteMessages,
-                          base::Unretained(this), route_id));
+    SetWakeReason(
+        MediaRouteProviderWakeReason::START_LISTENING_FOR_ROUTE_MESSAGES);
+    RunOrDefer(
+        base::Bind(&MediaRouterMojoImpl::DoStartListeningForRouteMessages,
+                   base::Unretained(this), route_id));
   }
 }
 
@@ -710,24 +713,15 @@ void MediaRouterMojoImpl::DoSendSessionBinaryMessage(
                                                 callback);
 }
 
-void MediaRouterMojoImpl::DoListenForRouteMessages(
+void MediaRouterMojoImpl::DoStartListeningForRouteMessages(
     const MediaRoute::Id& route_id) {
-  DVLOG_WITH_INSTANCE(1) << "ListenForRouteMessages";
-  if (!ContainsValue(route_ids_listening_for_messages_, route_id)) {
-    route_ids_listening_for_messages_.insert(route_id);
-    media_route_provider_->ListenForRouteMessages(
-        route_id, base::Bind(&MediaRouterMojoImpl::OnRouteMessagesReceived,
-                             base::Unretained(this), route_id));
-  }
+  DVLOG_WITH_INSTANCE(1) << "DoStartListeningForRouteMessages";
+  media_route_provider_->StartListeningForRouteMessages(route_id);
 }
 
 void MediaRouterMojoImpl::DoStopListeningForRouteMessages(
     const MediaRoute::Id& route_id) {
   DVLOG_WITH_INSTANCE(1) << "StopListeningForRouteMessages";
-
-  // No need to erase |route_ids_listening_for_messages_| entry here.
-  // It will be removed when there are no more observers by the time
-  // |OnRouteMessagesReceived| is invoked.
   media_route_provider_->StopListeningForRouteMessages(route_id);
 }
 
@@ -747,49 +741,29 @@ void MediaRouterMojoImpl::DoSearchSinks(
 }
 
 void MediaRouterMojoImpl::OnRouteMessagesReceived(
-    const MediaRoute::Id& route_id,
-    mojo::Array<interfaces::RouteMessagePtr> messages,
-    bool error) {
-  DVLOG(1) << "OnRouteMessagesReceived";
-
-  // If |messages| is null, then no more messages will come from this route.
-  // We can stop listening.
-  if (error) {
-    DVLOG(2) << "Encountered error in OnRouteMessagesReceived for " << route_id;
-    route_ids_listening_for_messages_.erase(route_id);
-    return;
-  }
+    const mojo::String& route_id,
+    mojo::Array<interfaces::RouteMessagePtr> messages) {
+  DVLOG_WITH_INSTANCE(1) << "OnRouteMessagesReceived";
+
+  DCHECK(!messages.storage().empty());
 
-  // Check if there are any observers remaining. If not, the messages
-  // can be discarded and we can stop listening for the next batch of messages.
   auto* observer_list = messages_observers_.get(route_id);
   if (!observer_list) {
-    route_ids_listening_for_messages_.erase(route_id);
     return;
   }
 
-  // If |messages| is empty, then |StopListeningForRouteMessages| was invoked
-  // but we have added back an observer since. Keep listening for more messages,
-  // but do not notify observers with empty list.
-  if (!messages.storage().empty()) {
-    ScopedVector<content::PresentationSessionMessage> session_messages;
-    session_messages.reserve(messages.size());
-    for (size_t i = 0; i < messages.size(); ++i) {
-      session_messages.push_back(
-          ConvertToPresentationSessionMessage(std::move(messages[i])));
-    }
-    base::ObserverList<PresentationSessionMessagesObserver>::Iterator
-        observer_it(observer_list);
-    bool single_observer =
-        observer_it.GetNext() != nullptr && observer_it.GetNext() == nullptr;
-    FOR_EACH_OBSERVER(PresentationSessionMessagesObserver, *observer_list,
-                      OnMessagesReceived(session_messages, single_observer));
+  ScopedVector<content::PresentationSessionMessage> session_messages;
+  session_messages.reserve(messages.size());
+  for (size_t i = 0; i < messages.size(); ++i) {
+    session_messages.push_back(
+        ConvertToPresentationSessionMessage(std::move(messages[i])));
   }
-
-  // Listen for more messages.
-  media_route_provider_->ListenForRouteMessages(
-      route_id, base::Bind(&MediaRouterMojoImpl::OnRouteMessagesReceived,
-                           base::Unretained(this), route_id));
+  base::ObserverList<PresentationSessionMessagesObserver>::Iterator observer_it(
+      observer_list);
+  bool single_observer =
+      observer_it.GetNext() != nullptr && observer_it.GetNext() == nullptr;
+  FOR_EACH_OBSERVER(PresentationSessionMessagesObserver, *observer_list,
+                    OnMessagesReceived(session_messages, single_observer));
 }
 
 void MediaRouterMojoImpl::OnSinkAvailabilityUpdated(