Merge 140879

Source/WebCore/Modules/webaudio/AudioScheduledSourceNode.cpp

 /*
  * Copyright (C) 2012, 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 99 matching lines @@
     // If the end time is somewhere in the middle of this time quantum, then zero out the
     // frames from the end time to the very end of the quantum.
     if (m_endTime != UnknownTime && endFrame >= quantumStartFrame && endFrame < quantumEndFrame) {
         size_t zeroStartFrame = endFrame - quantumStartFrame;
         size_t framesToZero = quantumFrameSize - zeroStartFrame;
 
         bool isSafe = zeroStartFrame < quantumFrameSize && framesToZero <= quantumFrameSize && zeroStartFrame + framesToZero <= quantumFrameSize;
         ASSERT(isSafe);
 
         if (isSafe) {
-            nonSilentFramesToProcess -= framesToZero;
+            if (framesToZero > nonSilentFramesToProcess)
+                nonSilentFramesToProcess = 0;
+            else
+                nonSilentFramesToProcess -= framesToZero;
+
             for (unsigned i = 0; i < outputBus->numberOfChannels(); ++i)
                 memset(outputBus->channel(i)->mutableData() + zeroStartFrame, 0, sizeof(float) * framesToZero);
         }
 
         finish();
     }
 
     return;
 }
 
@@ skipping 35 matching lines @@
         // Let the context dereference this AudioNode.
         context()->notifyNodeFinishedProcessing(this);
         m_playbackState = FINISHED_STATE;
         context()->decrementActiveSourceCount();
     }
 }
 
 } // namespace WebCore
 
 #endif // ENABLE(WEB_AUDIO)