Guarantee a thread safety when accessing source location info in pannerNode.

Source/modules/webaudio/PannerNode.h

Index: Source/modules/webaudio/PannerNode.h
diff --git a/Source/modules/webaudio/PannerNode.h b/Source/modules/webaudio/PannerNode.h
index 3f5ef90618a2ba36a15dfe43c0675e7e40552d7f..76c10aa1a4d4e0bfdcb623d03559aa7a477d79cb 100644
--- a/Source/modules/webaudio/PannerNode.h
+++ b/Source/modules/webaudio/PannerNode.h
@@ -176,8 +176,8 @@ private:
     // AudioContext's connection count
     unsigned m_connectionCount;
 
-    // Synchronize process() and setPanningModel() which can change the panner.
-    mutable Mutex m_pannerLock;
+    // Synchronize process() and setters panningModel, distanceModel and source location info.

[Raymond Toy, 2014/03/13 21:37:46]

Update comment:

// Synchronize process() with setting of the panning model, distance model, and
caching of the source location/orientation info.

[KhNo, 2014/03/14 10:39:58]

Done.

[Raymond Toy, 2014/03/14 22:30:36]

Please use this comment. Your replacement is not quite the same and doesn't read
quite right.

[KhNo, 2014/03/15 04:58:16]

Done.

+    mutable Mutex m_processLock;

[Raymond Toy, 2014/03/13 21:37:46]

Why change the name?

[KhNo, 2014/03/14 10:39:58]

Previous code only has locked for m_panner which is for panningModel.
Now, there are additional things have to lock such as distanceModel, location
info...
In General, other source about web audio named m_processLock when there is
something to lock during excute process().

[Raymond Toy, 2014/03/14 22:30:36]

Ok.

 };
 
 } // namespace WebCore