Web Audio: when media playback requires a user gesture, apply rule to cross origin iframes.

third_party/WebKit/Source/modules/webaudio/BaseAudioContext.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 226 matching lines @@
 
     // Returns the maximum numuber of channels we can support.
     static unsigned maxNumberOfChannels() { return MaxNumberOfChannels;}
 
     // EventTarget
     const AtomicString& interfaceName() const final;
     ExecutionContext* getExecutionContext() const final;
 
     DEFINE_ATTRIBUTE_EVENT_LISTENER(statechange);
 
+    // Start the AudioContext. `isAllowedToStart()` MUST be called before.
     void startRendering();
+
     void notifyStateChange();
 
     // A context is considered closed if:
     //  - closeContext() has been called.
     //  - it has been stopped by its execution context.
     virtual bool isContextClosed() const { return m_isCleared; }
 
     // Get the security origin for this audio context.
     SecurityOrigin* getSecurityOrigin() const;
 
     // Get the PeriodicWave for the specified oscillator type.  The table is initialized internally
     // if necessary.
     PeriodicWave* periodicWave(int type);
 
-    // Check whether the AudioContext requires a user gesture and whether the
-    // current stack is processing user gesture and record these information in
-    // a histogram.
-    void recordUserGestureState();
-
 protected:
     explicit BaseAudioContext(Document*);
     BaseAudioContext(Document*, unsigned numberOfChannels, size_t numberOfFrames, float sampleRate);
 
     void initialize();
     void uninitialize();
 
     void setContextState(AudioContextState);
 
     virtual void didClose() {}
 
     // Tries to handle AudioBufferSourceNodes that were started but became disconnected or was never
     // connected. Because these never get pulled anymore, they will stay around forever. So if we
     // can, try to stop them so they can be collected.
     void handleStoppableSourceNodes();
 
     Member<AudioDestinationNode> m_destinationNode;
 
     // FIXME(dominicc): Move m_resumeResolvers to AudioContext, because only
     // it creates these Promises.
     // Vector of promises created by resume(). It takes time to handle them, so we collect all of
     // the promises here until they can be resolved or rejected.
     HeapVector<Member<ScriptPromiseResolver>> m_resumeResolvers;
 
     void setClosedContextSampleRate(float newSampleRate) { m_closedContextSampleRate = newSampleRate; }
     float closedContextSampleRate() const { return m_closedContextSampleRate; }
 
     void rejectPendingDecodeAudioDataResolvers();
 
+    // If any, unlock user gesture requirements if a user gesture is being
+    // processed.
+    void maybeUnlockUserGesture();
+
+    // Returns whether the AudioContext is allowed to start rendering.
+    bool isAllowedToStart() const;
+
 private:
     bool m_isCleared;
     void clear();
 
     // When the context goes away, there might still be some sources which
     // haven't finished playing.  Make sure to release them here.
     void releaseActiveSourceNodes();
 
     void removeFinishedSourceNodes();
 
@@ skipping 64 matching lines @@
     Member<PeriodicWave> m_periodicWaveTriangle;
 
     // This is considering 32 is large enough for multiple channels audio.
     // It is somewhat arbitrary and could be increased if necessary.
     enum { MaxNumberOfChannels = 32 };
 };
 
 } // namespace blink
 
 #endif // BaseAudioContext_h