Keep AudioSourceNode from premature GC with ScriptWrappable::hasPendingActivity()

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

 /*
  * Copyright (C) 2012, 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 215 matching lines @@
 AudioScheduledSourceNode::AudioScheduledSourceNode(AbstractAudioContext& context)
     : AudioSourceNode(context)
 {
 }
 
 AudioScheduledSourceHandler& AudioScheduledSourceNode::audioScheduledSourceHandler() const
 {
     return static_cast<AudioScheduledSourceHandler&>(handler());
 }
 
-void AudioScheduledSourceNode::start(ExceptionState& exceptionState)
+void AudioScheduledSourceNode::startNode(ExceptionState& exceptionState)
 {
-    start(0, exceptionState);
+    startNode(0, exceptionState);
 }
 
-void AudioScheduledSourceNode::start(double when, ExceptionState& exceptionState)
+void AudioScheduledSourceNode::startNode(double when, ExceptionState& exceptionState)
 {
     audioScheduledSourceHandler().start(when, exceptionState);
 }
 
-void AudioScheduledSourceNode::stop(ExceptionState& exceptionState)
+void AudioScheduledSourceNode::stopNode(ExceptionState& exceptionState)
 {
-    stop(0, exceptionState);
+    stopNode(0, exceptionState);
 }
 
-void AudioScheduledSourceNode::stop(double when, ExceptionState& exceptionState)
+void AudioScheduledSourceNode::stopNode(double when, ExceptionState& exceptionState)
 {
     audioScheduledSourceHandler().stop(when, exceptionState);
 }
 
 EventListener* AudioScheduledSourceNode::onended()
 {
     return getAttributeEventListener(EventTypeNames::ended);
 }
 
 void AudioScheduledSourceNode::setOnended(PassRefPtrWillBeRawPtr<EventListener> listener)
 {
     setAttributeEventListener(EventTypeNames::ended, listener);
 }
 
+bool AudioScheduledSourceNode::hasPendingActivity() const
+{
+    // It is possible to play a source node for a very long time or to schedule
+    // too far in the future; thus infinitely playing/scheduled sources leak
+    // after the execution context is torn down because |hasPendingActivity|
+    // still returns true.

[Raymond Toy, 2016/02/22 17:43:51]

Don't think this comment really adds anything.  I think the comment at line 173+
pretty much explains why you're returning false.

[hongchan, 2016/02/23 18:01:33]

Where is the comment at line 173?

[Raymond Toy, 2016/02/23 18:12:05]

Oops.  273, the lines below.

+    //
+    // To avoid the leak, a node should be collected regardless of its
+    // playback state if the context is closed.
+    if (context()->isContextClosed())
+        return false;
+
+    // If a node is scheduled or playing, do not collect the node prematurely
+    // even its reference is out of scope. (and fire onended event if assigned)

[Raymond Toy, 2016/02/22 17:43:51]

Typo: "(and fire" -> "And fire".

[hongchan, 2016/02/23 18:01:33]

Done.

+    return audioScheduledSourceHandler().isPlayingOrScheduled();
+}
+
 } // namespace blink