Add UMA histogramm for AudioContext.getOutputTimestamp()

third_party/WebKit/Source/modules/webaudio/AudioContext.idl

 /*
  * Copyright (C) 2010, Google Inc. All rights reserved.
  * Copyright (C) 2011 Apple 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
@@ skipping 19 matching lines @@
     Constructor,
     ConstructorCallWith=Document,
     DependentLifetime,
     RaisesException=Constructor,
     Measure
 ] interface AudioContext : BaseAudioContext {
     [MeasureAs=AudioContextSuspend, CallWith=ScriptState, ImplementedAs=suspendContext] Promise<void> suspend();
     [MeasureAs=AudioContextClose, CallWith=ScriptState, ImplementedAs=closeContext] Promise<void> close();
 
     // Output timestamp
-    [CallWith=ScriptState] AudioTimestamp getOutputTimestamp();
+    [MeasureAs=AudioContextGetOutputTimestamp, CallWith=ScriptState] AudioTimestamp getOutputTimestamp();
 
     // Sources
     // TODO(rtoy): The following methods should be here instead of in BaseAudioContext:
     //
     // createMediaElementSource(HTMLMediaElement mediaElement)
     // createMediaStreamSource(MediaStream mediaStream)
     // createMediaStreamDestination()
 };