[MediaSession] Add playbackState attribute to Blink MediaSession and use it to determine playback s…

content/browser/media/session/media_session_service_impl.cc

Index: content/browser/media/session/media_session_service_impl.cc
diff --git a/content/browser/media/session/media_session_service_impl.cc b/content/browser/media/session/media_session_service_impl.cc
index 6c9ce1f436263a3dc3a3e284c8abf9284574809e..1d93af395a1768bfd000c226d51b0d862230ebf8 100644
--- a/content/browser/media/session/media_session_service_impl.cc
+++ b/content/browser/media/session/media_session_service_impl.cc
@@ -14,7 +14,8 @@ namespace content {
 
 MediaSessionServiceImpl::MediaSessionServiceImpl(
     RenderFrameHost* render_frame_host)
-    : render_frame_host_(render_frame_host) {
+    : render_frame_host_(render_frame_host),
+      playback_state_(blink::mojom::MediaSessionPlaybackState::NONE) {
   MediaSessionImpl* session = GetMediaSession();
   if (session)
     session->OnServiceCreated(this);
@@ -40,6 +41,14 @@ void MediaSessionServiceImpl::SetClient(
   client_ = std::move(client);
 }
 
+void MediaSessionServiceImpl::SetPlaybackState(
+    blink::mojom::MediaSessionPlaybackState state) {
+  playback_state_ = state;
+  MediaSessionImpl* session = GetMediaSession();
+  if (session)
+    session->OnMediaSessionPlaybackStateChanged(this);
+}
+
 void MediaSessionServiceImpl::SetMetadata(
     const base::Optional<content::MediaMetadata>& metadata) {
   // When receiving a MediaMetadata, the browser process can't trust that it is