Defer changes to channelInterpretation to pre/post rendering.

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

Index: third_party/WebKit/Source/modules/webaudio/AudioNode.cpp
diff --git a/third_party/WebKit/Source/modules/webaudio/AudioNode.cpp b/third_party/WebKit/Source/modules/webaudio/AudioNode.cpp
index 0e2320464e1b59c949d2bde59063b9e4e3f17f1f..bc6ccd61fe8dff82812cb360b1ded537322e0111 100644
--- a/third_party/WebKit/Source/modules/webaudio/AudioNode.cpp
+++ b/third_party/WebKit/Source/modules/webaudio/AudioNode.cpp
@@ -97,6 +97,7 @@ void AudioHandler::dispose()
     ASSERT(context()->isGraphOwner());
 
     context()->deferredTaskHandler().removeChangedChannelCountMode(this);
+    context()->deferredTaskHandler().removeChangedChannelInterpretation(this);
     context()->deferredTaskHandler().removeAutomaticPullNode(this);
     for (auto& output : m_outputs)
         output->dispose();
@@ -280,13 +281,18 @@ void AudioHandler::setChannelInterpretation(const String& interpretation, Except
     ASSERT(isMainThread());
     AbstractAudioContext::AutoLocker locker(context());
 
+    AudioBus::ChannelInterpretation oldMode = m_channelInterpretation;
+
     if (interpretation == "speakers") {
-        m_channelInterpretation = AudioBus::Speakers;
+        m_newChannelInterpretation = AudioBus::Speakers;
     } else if (interpretation == "discrete") {
-        m_channelInterpretation = AudioBus::Discrete;
+        m_newChannelInterpretation = AudioBus::Discrete;
     } else {
         ASSERT_NOT_REACHED();
     }
+
+    if (m_newChannelInterpretation != oldMode)
+        context()->deferredTaskHandler().addChangedChannelInterpretation(this);
 }
 
 void AudioHandler::updateChannelsForInputs()
@@ -506,6 +512,11 @@ void AudioHandler::updateChannelCountMode()
     updateChannelsForInputs();
 }
 
+void AudioHandler::updateChannelInterpretation()
+{
+    m_channelInterpretation = m_newChannelInterpretation;
+}
+
 unsigned AudioHandler::numberOfOutputChannels() const
 {
     // This should only be called for ScriptProcessorNodes which are the only nodes where you can