Implement suspend() and resume() for OfflineAudioContext

third_party/WebKit/Source/modules/webaudio/AbstractAudioContext.cpp

 /*
  * Copyright (C) 2010, 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:
  * 1.  Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
  * 2.  Redistributions in binary form must reproduce the above copyright
  *    notice, this list of conditions and the following disclaimer in the
@@ skipping 64 matching lines @@
 {
     return AudioContext::create(document, exceptionState);
 }
 
 // FIXME(dominicc): Devolve these constructors to AudioContext
 // and OfflineAudioContext respectively.
 
 // Constructor for rendering to the audio hardware.
 AbstractAudioContext::AbstractAudioContext(Document* document)
     : ActiveDOMObject(document)
+    , m_destinationNode(nullptr)
     , m_isCleared(false)
-    , m_destinationNode(nullptr)
     , m_isResolvingResumePromises(false)
     , m_connectionCount(0)
     , m_didInitializeContextGraphMutex(false)
     , m_deferredTaskHandler(DeferredTaskHandler::create())
     , m_contextState(Suspended)
 {
     m_didInitializeContextGraphMutex = true;
     m_destinationNode = DefaultAudioDestinationNode::create(this);
 
     initialize();
 }
 
 // Constructor for offline (non-realtime) rendering.
 AbstractAudioContext::AbstractAudioContext(Document* document, unsigned numberOfChannels, size_t numberOfFrames, float sampleRate)
     : ActiveDOMObject(document)
+    , m_destinationNode(nullptr)
     , m_isCleared(false)
-    , m_destinationNode(nullptr)
     , m_isResolvingResumePromises(false)
     , m_connectionCount(0)
     , m_didInitializeContextGraphMutex(false)
     , m_deferredTaskHandler(DeferredTaskHandler::create())
     , m_contextState(Suspended)
 {
     m_didInitializeContextGraphMutex = true;

[Raymond Toy, 2015/10/16 23:32:36]

Why is this initialized to true here and false in line 106?

(Not part of your CL. I just noticed this.)

[hongchan, 2015/10/19 20:08:12]

It has been like this from the beginning. Honestly I couldn't figure out why,
but I assumed that the mutex is false before the actual execution of constructor
and the timing might be important?

-    // Create a new destination for offline rendering.
-    m_renderTarget = AudioBuffer::create(numberOfChannels, numberOfFrames, sampleRate);
-    if (m_renderTarget.get())
-        m_destinationNode = OfflineAudioDestinationNode::create(this, m_renderTarget.get());
-
-    initialize();
 }
 
 AbstractAudioContext::~AbstractAudioContext()
 {
     deferredTaskHandler().contextWillBeDestroyed();
     // AudioNodes keep a reference to their context, so there should be no way to be in the destructor if there are still AudioNodes around.
     ASSERT(!isDestinationInitialized());
     ASSERT(!m_activeSourceNodes.size());
     ASSERT(!m_finishedSourceHandlers.size());
     ASSERT(!m_isResolvingResumePromises);
@@ skipping 670 matching lines @@
     // This is called for both online and offline contexts.
     ASSERT(isMainThread());
     ASSERT(m_destinationNode);
 
     if (m_contextState == Suspended) {
         destination()->audioDestinationHandler().startRendering();
         setContextState(Running);
     }
 }
 
-void AbstractAudioContext::fireCompletionEvent()
-{
-    ASSERT(isMainThread());
-    if (!isMainThread())
-        return;
-
-    AudioBuffer* renderedBuffer = m_renderTarget.get();
-
-    // For an offline context, we set the state to closed here so that the oncomplete handler sees
-    // that the context has been closed.
-    setContextState(Closed);
-
-    ASSERT(renderedBuffer);
-    if (!renderedBuffer)
-        return;
-
-    // Avoid firing the event if the document has already gone away.
-    if (executionContext()) {
-        // Call the offline rendering completion event listener and resolve the promise too.
-        dispatchEvent(OfflineAudioCompletionEvent::create(renderedBuffer));
-        m_offlineResolver->resolve(renderedBuffer);
-    }
-}
-
 DEFINE_TRACE(AbstractAudioContext)
 {
-    visitor->trace(m_offlineResolver);
-    visitor->trace(m_renderTarget);
     visitor->trace(m_destinationNode);
     visitor->trace(m_listener);
     // trace() can be called in AbstractAudioContext constructor, and
     // m_contextGraphMutex might be unavailable.
     if (m_didInitializeContextGraphMutex) {
         AutoLocker lock(this);
         visitor->trace(m_activeSourceNodes);
     } else {
         visitor->trace(m_activeSourceNodes);
     }
     visitor->trace(m_resumeResolvers);
     RefCountedGarbageCollectedEventTargetWithInlineData<AbstractAudioContext>::trace(visitor);
     ActiveDOMObject::trace(visitor);
 }
 
 SecurityOrigin* AbstractAudioContext::securityOrigin() const
 {
     if (executionContext())
         return executionContext()->securityOrigin();
 
     return nullptr;
 }
 
 } // namespace blink
 
 #endif // ENABLE(WEB_AUDIO)