Oilpan: have the media element safely close its MediaSource.

Source/modules/mediasource/MediaSource.cpp

 /*
  * Copyright (C) 2013 Google Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are
  * met:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
  *     * Redistributions in binary form must reproduce the above
@@ skipping 80 matching lines @@
 {
     MediaSource* mediaSource(adoptRefCountedGarbageCollected(new MediaSource(context)));
     mediaSource->suspendIfNeeded();
     return mediaSource;
 }
 
 MediaSource::MediaSource(ExecutionContext* context)
     : ActiveDOMObject(context)
     , m_readyState(closedKeyword())
     , m_asyncEventQueue(GenericEventQueue::create(this))
-    , m_attachedElement(0)
+    , m_attachedElement(nullptr)
     , m_sourceBuffers(SourceBufferList::create(executionContext(), m_asyncEventQueue.get()))
     , m_activeSourceBuffers(SourceBufferList::create(executionContext(), m_asyncEventQueue.get()))
 {
     WTF_LOG(Media, "MediaSource::MediaSource %p", this);
     ScriptWrappable::init(this);
 }
 
 MediaSource::~MediaSource()
 {
     WTF_LOG(Media, "MediaSource::~MediaSource %p", this);
+#if !ENABLE(OILPAN)
     ASSERT(isClosed());
+#endif
 }
 
 SourceBuffer* MediaSource::addSourceBuffer(const String& type, ExceptionState& exceptionState)
 {
     WTF_LOG(Media, "MediaSource::addSourceBuffer(%s) %p", type.ascii().data(), this);
 
     // 2.2 https://dvcs.w3.org/hg/html-media/raw-file/default/media-source/media-source.html#widl-MediaSource-addSourceBuffer-SourceBuffer-DOMString-type
     // 1. If type is an empty string then throw an InvalidAccessError exception
     // and abort these steps.
     if (type.isEmpty()) {
@@ skipping 127 matching lines @@
 const AtomicString& MediaSource::interfaceName() const
 {
     return EventTargetNames::MediaSource;
 }
 
 ExecutionContext* MediaSource::executionContext() const
 {
     return ActiveDOMObject::executionContext();
 }
 
+void MediaSource::clearWeakMembers(Visitor* visitor)
+{
+#if ENABLE(OILPAN)
+    // Oilpan: If the MediaSource survived, but its attached media
+    // element did not, signal the element that it can safely
+    // notify its MediaSource during finalization by calling close().

[haraken, 2014/07/03 09:46:05]

Also let's add a comment that m_attachedElement is cleared when the
HTMLMediaElement is destructed (or simply add code to clear m_attachedElement
here).

[sof, 2014/07/03 09:49:00]

Oh, I'm sorry - I merely forgot to follow up on your earlier suggestion. I agree
that we should clear it in the weak callback; will do.

+    if (m_attachedElement && !visitor->isAlive(m_attachedElement))
+        m_attachedElement->setCloseMediaSourceWhenFinalizing();
+#endif
+}
+
 void MediaSource::trace(Visitor* visitor)
 {
 #if ENABLE(OILPAN)
     visitor->trace(m_asyncEventQueue);
 #endif
     visitor->trace(m_sourceBuffers);
     visitor->trace(m_activeSourceBuffers);
+    visitor->registerWeakMembers<MediaSource, &MediaSource::clearWeakMembers>(this);
     EventTargetWithInlineData::trace(visitor);
 }
 
 void MediaSource::setWebMediaSourceAndOpen(PassOwnPtr<WebMediaSource> webMediaSource)
 {
     TRACE_EVENT_ASYNC_END0("media", "MediaSource::attachToElement", this);
     ASSERT(webMediaSource);
     ASSERT(!m_webMediaSource);
     ASSERT(m_attachedElement);
     m_webMediaSource = webMediaSource;
@@ skipping 119 matching lines @@
 
 void MediaSource::setReadyState(const AtomicString& state)
 {
     ASSERT(state == openKeyword() || state == closedKeyword() || state == endedKeyword());
 
     AtomicString oldState = readyState();
     WTF_LOG(Media, "MediaSource::setReadyState() %p : %s -> %s", this, oldState.ascii().data(), state.ascii().data());
 
     if (state == closedKeyword()) {
         m_webMediaSource.clear();
-        m_attachedElement = 0;
+        m_attachedElement = nullptr;
     }
 
     if (oldState == state)
         return;
 
     m_readyState = state;
 
     onReadyStateChange(oldState, state);
 }
 
@@ skipping 123 matching lines @@
 
     m_asyncEventQueue->enqueueEvent(event.release());
 }
 
 URLRegistry& MediaSource::registry() const
 {
     return MediaSourceRegistry::registry();
 }
 
 } // namespace WebCore