Implementation of 'AudioContext.getOutputTimestamp' method

third_party/WebKit/public/platform/WebAudioDevice.h

 /*
  * Copyright (C) 2010 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
@@ skipping 17 matching lines @@
 
 #ifndef WebAudioDevice_h
 #define WebAudioDevice_h
 
 #include "WebCommon.h"
 #include "WebVector.h"
 
 namespace blink {
 
 // Abstract interface to the Chromium audio system.
-
 class WebAudioDevice {
  public:
   class BLINK_PLATFORM_EXPORT RenderCallback {
    public:
+    // Note: |delay| and |delayTimestamp| arguments are high-precision
+    // measurements of the state of the system in the recent past. To be clear,
+    // |delay| does *not* represent the point-in-time at which the first
+    // rendered sample will be played out.
     virtual void render(const WebVector<float*>& sourceData,
                         const WebVector<float*>& destinationData,
-                        size_t numberOfFrames);
+                        size_t numberOfFrames,
+                        double delay,           // Output delay in seconds.
+                        double delayTimestamp,  // System timestamp in seconds
+                                                // when |delay| was obtained.
+                        size_t priorFramesSkipped);
 
    protected:
     virtual ~RenderCallback();
   };
 
   virtual ~WebAudioDevice() {}
 
   virtual void start() = 0;
   virtual void stop() = 0;
   virtual double sampleRate() = 0;
 };
 
 }  // namespace blink
 
 #endif  // WebAudioDevice_h