Cleanup on RemotePlayback stop

Currently, successfully starting/stopping/starting RemotePlayback runs
into a DCHECK, because we never properly clean up on RemotePlayback
stop. This CL fixes the issue and gets rid of a TODO.

Bug: 790766
Change-Id: Ieca32cd175741e5c1ae7e55879ae4a224d67b76c
Reviewed-on: https://chromium-review.googlesource.com/c/1260282Reviewed-by: Mounir Lamouri <mlamouri@chromium.org>
Commit-Queue: Thomas Guilbert <tguilbert@chromium.org>
Cr-Commit-Position: refs/heads/master@{#596435}

third_party/blink/renderer/modules/remoteplayback/remote_playback.cc

@@ -227,8 +227,7 @@ bool RemotePlayback::HasPendingActivity() const {
 }
 
 void RemotePlayback::ContextDestroyed(ExecutionContext*) {
-  target_presentation_connection_.reset();
-  presentation_connection_binding_.Close();
+  CleanupConnections();
 }
 
 void RemotePlayback::PromptInternal() {
@@ -369,7 +368,9 @@ void RemotePlayback::StateChanged(WebRemotePlaybackState state) {
               ->MediaRemotingStopped(
                   WebLocalizedString::kMediaRemotingStopNoText);
         }
+        CleanupConnections();
         presentation_id_ = "";
+        presentation_url_ = KURL();
         media_element_->FlingingStopped();
       }
       break;
@@ -465,6 +466,11 @@ void RemotePlayback::RemotePlaybackDisabled() {
   }
 }
 
+void RemotePlayback::CleanupConnections() {
+  target_presentation_connection_.reset();
+  presentation_connection_binding_.Close();
+}
+
 void RemotePlayback::AvailabilityChanged(
     mojom::blink::ScreenAvailability availability) {
   DCHECK(RuntimeEnabledFeatures::NewRemotePlaybackPipelineEnabled());
@@ -511,7 +517,6 @@ void RemotePlayback::OnConnectionSuccess(
 
   StateChanged(WebRemotePlaybackState::kConnecting);
 
-  // TODO(imcheng): Reset binding when remote playback stops.
   DCHECK(!presentation_connection_binding_.is_bound());
   auto* presentation_controller =
       PresentationController::FromContext(GetExecutionContext());

third_party/blink/renderer/modules/remoteplayback/remote_playback.h

@@ -150,6 +150,9 @@ class MODULES_EXPORT RemotePlayback final
   // May be called more than once in a row.
   void StopListeningForAvailability();
 
+  // Clears bindings after remote playback stops.
+  void CleanupConnections();
+
   WebRemotePlaybackState state_;
   WebRemotePlaybackAvailability availability_;
   HeapHashMap<int, TraceWrapperMember<AvailabilityCallbackWrapper>>