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

third_party/WebKit/Source/modules/mediasession/MediaSession.cpp

Index: third_party/WebKit/Source/modules/mediasession/MediaSession.cpp
diff --git a/third_party/WebKit/Source/modules/mediasession/MediaSession.cpp b/third_party/WebKit/Source/modules/mediasession/MediaSession.cpp
index b723323b95aebfa0441d76589fd913e89b82099c..29e69d142da2e08dbf8e493dfbe59054b3940173 100644
--- a/third_party/WebKit/Source/modules/mediasession/MediaSession.cpp
+++ b/third_party/WebKit/Source/modules/mediasession/MediaSession.cpp
@@ -66,10 +66,41 @@ WTF::Optional<MediaSessionAction> eventNameToMojomAction(
   return WTF::nullopt;
 }
 
+const AtomicString& mediaSessionPlaybackStateToString(
+    mojom::blink::MediaSessionPlaybackState state) {
+  DEFINE_STATIC_LOCAL(const AtomicString, noneValue, ("none"));
+  DEFINE_STATIC_LOCAL(const AtomicString, pausedValue, ("paused"));
+  DEFINE_STATIC_LOCAL(const AtomicString, playingValue, ("playing"));
+
+  switch (state) {
+    case mojom::blink::MediaSessionPlaybackState::NONE:
+      return noneValue;
+    case mojom::blink::MediaSessionPlaybackState::PAUSED:
+      return pausedValue;
+    case mojom::blink::MediaSessionPlaybackState::PLAYING:
+      return playingValue;
+    default:
+      NOTREACHED();

[mlamouri (slow - plz ping), 2016/12/16 15:49:14]

No need for `default`, it will not compile if we add a new value which will
force us to handle it.

[Zhiqiang Zhang (Slow), 2016/12/16 18:26:15]

Done.

+  }
+  return WTF::emptyAtom;

[mlamouri (slow - plz ping), 2016/12/16 15:49:14]

NOTREACHED()?

[Zhiqiang Zhang (Slow), 2016/12/16 18:26:15]

Done.

+}
+
+mojom::blink::MediaSessionPlaybackState stringToMediaSessionPlaybackState(
+    const String& stateName) {
+  if (stateName == "none")
+    return mojom::blink::MediaSessionPlaybackState::NONE;
+  if (stateName == "paused")
+    return mojom::blink::MediaSessionPlaybackState::PAUSED;
+  DCHECK_EQ(stateName, "playing");
+  return mojom::blink::MediaSessionPlaybackState::PLAYING;
+}
+
 }  // anonymous namespace
 
 MediaSession::MediaSession(ExecutionContext* executionContext)
-    : ContextLifecycleObserver(executionContext), m_clientBinding(this) {}
+    : ContextLifecycleObserver(executionContext),
+      m_playbackState(mojom::blink::MediaSessionPlaybackState::NONE),
+      m_clientBinding(this) {}
 
 MediaSession* MediaSession::create(ExecutionContext* executionContext) {
   return new MediaSession(executionContext);
@@ -79,6 +110,17 @@ void MediaSession::dispose() {
   m_clientBinding.Close();
 }
 
+void MediaSession::setPlaybackState(const String& playbackState) {
+  m_playbackState = stringToMediaSessionPlaybackState(playbackState);
+  mojom::blink::MediaSessionService* service = getService();
+  if (service)
+    service->SetPlaybackState(m_playbackState);
+}
+
+String MediaSession::playbackState() {
+  return mediaSessionPlaybackStateToString(m_playbackState);
+}
+
 void MediaSession::setMetadata(MediaMetadata* metadata) {
   if (mojom::blink::MediaSessionService* service = getService()) {
     service->SetMetadata(MediaMetadataSanitizer::sanitizeAndConvertToMojo(