Output silence if the MediaElementAudioSourceNode has a different origin

Source/modules/webaudio/MediaElementAudioSourceNode.cpp

 /*
  * Copyright (C) 2011, 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 15 matching lines @@
 
 #if ENABLE(WEB_AUDIO)
 
 #include "modules/webaudio/MediaElementAudioSourceNode.h"
 
 #include "core/html/HTMLMediaElement.h"
 #include "modules/webaudio/AudioContext.h"
 #include "modules/webaudio/AudioNodeOutput.h"
 #include "platform/Logging.h"
 #include "platform/audio/AudioUtilities.h"
+#include "platform/graphics/media/MediaPlayer.h"
+#include "platform/weborigin/SecurityOrigin.h"
 #include "wtf/Locker.h"
 
 namespace blink {
 
 MediaElementAudioSourceNode* MediaElementAudioSourceNode::create(AudioContext* context, HTMLMediaElement* mediaElement)
 {
     return new MediaElementAudioSourceNode(context, mediaElement);
 }
 
 MediaElementAudioSourceNode::MediaElementAudioSourceNode(AudioContext* context, HTMLMediaElement* mediaElement)
@@ skipping 64 matching lines @@
         outputBus->zero();
         return;
     }
 
     // Use a tryLock() to avoid contention in the real-time audio thread.
     // If we fail to acquire the lock then the HTMLMediaElement must be in the middle of
     // reconfiguring its playback engine, so we output silence in this case.
     MutexTryLocker tryLocker(m_processLock);
     if (tryLocker.locked()) {
         if (AudioSourceProvider* provider = mediaElement()->audioSourceProvider()) {
+            // Grab data from the provider so that the element continues to make progress, even if
+            // we're going to output silence anyway.
             if (m_multiChannelResampler.get()) {
                 ASSERT(m_sourceSampleRate != sampleRate());
                 m_multiChannelResampler->process(provider, outputBus, numberOfFrames);
             } else {
                 // Bypass the resampler completely if the source is at the context's sample-rate.
                 ASSERT(m_sourceSampleRate == sampleRate());
                 provider->provideInput(outputBus, numberOfFrames);
             }
+            // Output silence if we don't have access to the element.
+            if (!(mediaElement()->webMediaPlayer()->didPassCORSAccessCheck()
+                || context()->securityOrigin()->canRequest(mediaElement()->currentSrc()))) {

[Ken Russell (switch to Gerrit), 2015/02/04 01:28:19]

The indentation looks confusing here. I'd indent the || a couple more spaces to
be on the right hand side of the inner open-paren.
http://www.chromium.org/blink/coding-style#TOC-Line-breaking (not really covered
there)

[Raymond Toy, 2015/02/04 19:00:38]

Clang-format puts || under the "d" in mediaElement, which is nicer.

+                outputBus->zero();
+            }
         } else {
             // Either this port doesn't yet support HTMLMediaElement audio stream access,
             // or the stream is not yet available.
             outputBus->zero();
         }
     } else {
         // We failed to acquire the lock.
         outputBus->zero();
     }
 }
@@ skipping 11 matching lines @@
 void MediaElementAudioSourceNode::trace(Visitor* visitor)
 {
     visitor->trace(m_mediaElement);
     AudioSourceNode::trace(visitor);
     AudioSourceProviderClient::trace(visitor);
 }
 
 } // namespace blink
 
 #endif // ENABLE(WEB_AUDIO)