Treat a stopped AudioContext as closed.

Source/modules/webaudio/AudioContext.h

 /*
  * 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 204 matching lines @@
     virtual const AtomicString& interfaceName() const override final;
     virtual ExecutionContext* executionContext() const override final;
 
     DEFINE_ATTRIBUTE_EVENT_LISTENER(complete);
     DEFINE_ATTRIBUTE_EVENT_LISTENER(statechange);
 
     void startRendering();
     void fireCompletionEvent();
     void notifyStateChange();
 
-    // A context is considered closed if closeContext() has been called, even if the audio HW has
-    // not yet been stopped.  It will be stopped eventually.
-    bool isContextClosed() const { return m_closeResolver; }
+    // A context is considered closed if:
+    //  - closeContext() has been called, even if the audio HW has not yet been
+    //    stopped.  It will be stopped eventually.
+    //  - it has been stopped (or is stopping) by its execution context.
+    bool isContextClosed() const { return m_closeResolver || m_isStopScheduled || m_isCleared; }
 
     static unsigned s_hardwareContextCount;
     static unsigned s_contextId;
 
     // Get the security origin for this audio context.
     SecurityOrigin* securityOrigin() const;
 
 protected:
     explicit AudioContext(Document*);
     AudioContext(Document*, unsigned numberOfChannels, size_t numberOfFrames, float sampleRate);
@@ skipping 86 matching lines @@
     // This is considering 32 is large enough for multiple channels audio.
     // It is somewhat arbitrary and could be increased if necessary.
     enum { MaxNumberOfChannels = 32 };
 
     unsigned m_contextId;
 };
 
 } // namespace blink
 
 #endif // AudioContext_h