Defer changes to channelInterpretation to pre/post rendering.

third_party/WebKit/Source/modules/webaudio/DeferredTaskHandler.h

Index: third_party/WebKit/Source/modules/webaudio/DeferredTaskHandler.h
diff --git a/third_party/WebKit/Source/modules/webaudio/DeferredTaskHandler.h b/third_party/WebKit/Source/modules/webaudio/DeferredTaskHandler.h
index 7762706091e77c58fa7dd831b37512707bfe1b21..e4a65c4106c00f1f8034d085f9d1d219453ca6ec 100644
--- a/third_party/WebKit/Source/modules/webaudio/DeferredTaskHandler.h
+++ b/third_party/WebKit/Source/modules/webaudio/DeferredTaskHandler.h
@@ -79,6 +79,11 @@ public:
     void addChangedChannelCountMode(AudioHandler*);
     void removeChangedChannelCountMode(AudioHandler*);
 
+    // Keep track of AudioNode's that have their channel interpretation
+    // changed. We process the changes in the post rendering phase.
+    void addChangedChannelInterpretation(AudioHandler*);
+    void removeChangedChannelInterpretation(AudioHandler*);
+
     // Only accessed when the graph lock is held.
     void markSummingJunctionDirty(AudioSummingJunction*);
     // Only accessed when the graph lock is held. Must be called on the main thread.
@@ -117,10 +122,8 @@ public:
     // MUST NOT be used in the real-time audio context.
     void offlineLock();
 
-#if ENABLE(ASSERT)

[Nico, 2016/05/27 13:09:33]

You removed this here but not in the cc file. So now the function is declared
but not defined in non-assert builds. Things generally build since nothing calls
this in non-assert builds -- but in release component builds the whole class is
exported and hence clients try to import this method and links fail
(https://build.chromium.org/p/chromium.fyi/builders/ClangToTWin%28dll%29/build...)

Rather than remove the ENABLE(ASSERT) in the cc file, I think it's better to add
it back here -- since things build, nothing needs this to be defined. And I
don't understand why you had to remove the #if in the other file.

     // Returns true if this thread owns the context's lock.
     bool isGraphOwner();
-#endif
 
     class MODULES_EXPORT AutoLocker {
         STACK_ALLOCATED();
@@ -157,6 +160,7 @@ private:
     DeferredTaskHandler();
     void updateAutomaticPullNodes();
     void updateChangedChannelCountMode();
+    void updateChangedChannelInterpretation();
     void handleDirtyAudioSummingJunctions();
     void handleDirtyAudioNodeOutputs();
     void deleteHandlersOnMainThread();
@@ -175,6 +179,8 @@ private:
     // not to disturb the running audio thread.
     HashSet<AudioHandler*> m_deferredCountModeChange;
 
+    HashSet<AudioHandler*> m_deferredChannelInterpretationChange;
+
     // These two HashSet must be accessed only when the graph lock is held.
     // These raw pointers are safe because their destructors unregister them.
     HashSet<AudioSummingJunction*> m_dirtySummingJunctions;