Implementation of 'AudioContext.getOutputTimestamp' method

media/base/audio_renderer_sink.h

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef MEDIA_BASE_AUDIO_RENDERER_SINK_H_
 #define MEDIA_BASE_AUDIO_RENDERER_SINK_H_
 
 #include <stdint.h>
 
 #include <string>
 
 #include "base/callback.h"
 #include "base/memory/ref_counted.h"
 #include "media/base/audio_bus.h"
 #include "media/base/audio_parameters.h"
 #include "media/base/output_device_info.h"
 #include "url/origin.h"
 
 namespace media {
 
+struct AudioTimestamp;
+
 // AudioRendererSink is an interface representing the end-point for
 // rendered audio.  An implementation is expected to
 // periodically call Render() on a callback object.
 
 class AudioRendererSink
     : public base::RefCountedThreadSafe<media::AudioRendererSink> {
  public:
-  class RenderCallback {
+  class MEDIA_EXPORT RenderCallback {
    public:
     // Attempts to completely fill all channels of |dest|, returns actual
     // number of frames filled. |frames_skipped| contains the number of frames
     // the consumer has skipped, if any.
     virtual int Render(AudioBus* dest,
                        uint32_t frames_delayed,
-                       uint32_t frames_skipped) = 0;
+                       uint32_t frames_skipped);
+    // An alternate version which provides also device stream position,
+    // if not overriden it just invokes the method above.
+    virtual int Render(AudioBus* dest,
+                       uint32_t audio_delay_milliseconds,
+                       uint32_t frames_skipped,
+                       const AudioTimestamp& output_timestamp);
 
     // Signals an error has occurred.
     virtual void OnRenderError() = 0;
 
    protected:
     virtual ~RenderCallback() {}
   };
 
   // Sets important information about the audio stream format.
   // It must be called before any of the other methods.
@@ skipping 55 matching lines @@
                                   const url::Origin& security_origin,
                                   const OutputDeviceStatusCB& callback) = 0;
 
  protected:
   ~SwitchableAudioRendererSink() override {}
 };
 
 }  // namespace media
 
 #endif  // MEDIA_BASE_AUDIO_RENDERER_SINK_H_