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

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

 // Copyright 2015 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "modules/mediasession/MediaSession.h"
 
 #include "core/dom/Document.h"
 #include "core/dom/DocumentUserGestureToken.h"
 #include "core/dom/ExecutionContext.h"
 #include "core/events/Event.h"
@@ skipping 48 matching lines @@
     return MediaSessionAction::NEXT_TRACK;
   if (EventTypeNames::seekbackward == eventName)
     return MediaSessionAction::SEEK_BACKWARD;
   if (EventTypeNames::seekforward == eventName)
     return MediaSessionAction::SEEK_FORWARD;
 
   NOTREACHED();
   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);
 }
 
 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(
         metadata, getExecutionContext()));
   }
 }
 
 MediaMetadata* MediaSession::metadata() const {
   return m_metadata;
 }
@@ skipping 62 matching lines @@
   dispatchEvent(Event::create(mojomActionToEventName(action)));
 }
 
 DEFINE_TRACE(MediaSession) {
   visitor->trace(m_metadata);
   EventTargetWithInlineData::trace(visitor);
   ContextLifecycleObserver::trace(visitor);
 }
 
 }  // namespace blink