Remove ContextLifecycleObserver from MediaStream

third_party/WebKit/Source/modules/mediastream/MediaStream.h

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 #ifndef MediaStream_h
 #define MediaStream_h
 
-#include "core/dom/ContextLifecycleObserver.h"
+#include "core/dom/ExecutionContext.h"
 #include "core/html/URLRegistry.h"
 #include "modules/EventTargetModules.h"
 #include "modules/ModulesExport.h"
 #include "modules/mediastream/MediaStreamTrack.h"
 #include "platform/Timer.h"
 #include "platform/mediastream/MediaStreamDescriptor.h"
 
 namespace blink {
 
 class ExceptionState;
 
 class MODULES_EXPORT MediaStream final : public EventTargetWithInlineData,
                                          public URLRegistrable,
-                                         public MediaStreamDescriptorClient,
-                                         public ContextLifecycleObserver {
+                                         public MediaStreamDescriptorClient {
   USING_GARBAGE_COLLECTED_MIXIN(MediaStream);
   DEFINE_WRAPPERTYPEINFO();
 
  public:
   static MediaStream* create(ExecutionContext*);
   static MediaStream* create(ExecutionContext*, MediaStream*);
   static MediaStream* create(ExecutionContext*, const MediaStreamTrackVector&);
   static MediaStream* create(ExecutionContext*, MediaStreamDescriptor*);
   ~MediaStream() override;
 
@@ skipping 17 matching lines @@
 
   void trackEnded();
 
   // MediaStreamDescriptorClient
   void streamEnded() override;
 
   MediaStreamDescriptor* descriptor() const { return m_descriptor; }
 
   // EventTarget
   const AtomicString& interfaceName() const override;
-  ExecutionContext* getExecutionContext() const override;
+  ExecutionContext* getExecutionContext() const override {
+    return m_executionContext;
+  }
 
   // URLRegistrable
   URLRegistry& registry() const override;
 
   DECLARE_VIRTUAL_TRACE();
 
  protected:
   bool addEventListenerInternal(
       const AtomicString& eventType,
       EventListener*,
       const AddEventListenerOptionsResolved&) override;
 
  private:
   MediaStream(ExecutionContext*, MediaStreamDescriptor*);
   MediaStream(ExecutionContext*,
               const MediaStreamTrackVector& audioTracks,
               const MediaStreamTrackVector& videoTracks);
 
-  // ContextLifecycleObserver
-  void contextDestroyed() override;
-
   // MediaStreamDescriptorClient
   void addRemoteTrack(MediaStreamComponent*) override;
   void removeRemoteTrack(MediaStreamComponent*) override;
 
   bool emptyOrOnlyEndedTracks();
 
   void scheduleDispatchEvent(Event*);
   void scheduledEventTimerFired(TimerBase*);
 
-  bool m_stopped;
-
   MediaStreamTrackVector m_audioTracks;
   MediaStreamTrackVector m_videoTracks;
   Member<MediaStreamDescriptor> m_descriptor;
 
   Timer<MediaStream> m_scheduledEventTimer;
   HeapVector<Member<Event>> m_scheduledEvents;
+  Member<ExecutionContext> m_executionContext;

[haraken, 2016/12/07 06:35:01]

Before this CL, this was a weak member. However, I don't see any reason to make
it weak, so I changed it to a strong member.

[sof, 2016/12/07 07:34:16]

the worry/difference would be that downstream users of this object won't see a
null ExecutionContext after it has been "destroyed", which other implementations
of getExecutionContext() will provide. I haven't investigated if that makes a
substantive difference.

[haraken, 2016/12/07 08:05:52]

Yeah, good point.

Currently EventTarget::getExecutionContext() sometimes returns an
ExecutionContext backed by a WeakMember and sometimes returns an
ExecutionContext backed by a Member. So the difference won't matter.

 };
 
 typedef HeapVector<Member<MediaStream>> MediaStreamVector;
 
 MediaStream* toMediaStream(MediaStreamDescriptor*);
 
 }  // namespace blink
 
 #endif  // MediaStream_h