Express audio delay more precisely in frames rather than milliseconds.

media/base/audio_renderer_mixer.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_MIXER_H_
 #define MEDIA_BASE_AUDIO_RENDERER_MIXER_H_
 
 #include <stdint.h>
 
 #include <map>
@@ skipping 40 matching lines @@
   // parameters of the new device and the output parameters with which the
   // mixer was initialized. See crbug.com/506507
   OutputDevice* GetOutputDevice();
 
  private:
   // Maps input sample rate to the dedicated converter.
   typedef std::map<int, scoped_ptr<LoopbackAudioConverter>> AudioConvertersMap;
 
   // AudioRendererSink::RenderCallback implementation.
   int Render(AudioBus* audio_bus,
-             uint32_t audio_delay_milliseconds,
+             uint32_t frames_delayed,
              uint32_t frames_skipped) override;
   void OnRenderError() override;
 
   bool is_master_sample_rate(int sample_rate) {
     return sample_rate == output_params_.sample_rate();
   }
 
   // Output sink for this mixer.
   scoped_refptr<AudioRendererSink> audio_sink_;
 
   // Output parameters for this mixer.
   AudioParameters output_params_;
+  double microseconds_per_frame_;
 
   // ---------------[ All variables below protected by |lock_| ]---------------
   base::Lock lock_;
 
   // List of error callbacks used by this mixer.
   typedef std::list<base::Closure> ErrorCallbackList;
   ErrorCallbackList error_callbacks_;
 
   // Each of these converters mixes inputs with a given sample rate and
   // resamples them to the output sample rate. Inputs not reqiuring resampling
   // go directly to |master_converter_|.
   AudioConvertersMap converters_;
 
   // Master converter which mixes all the outputs from |converters_| as well as
   // mixer inputs that are in the output sample rate.
   AudioConverter master_converter_;
 
   // Handles physical stream pause when no inputs are playing.  For latency
   // reasons we don't want to immediately pause the physical stream.
   base::TimeDelta pause_delay_;
   base::TimeTicks last_play_time_;
   bool playing_;
 
   DISALLOW_COPY_AND_ASSIGN(AudioRendererMixer);
 };
 
 }  // namespace media
 
 #endif  // MEDIA_BASE_AUDIO_RENDERER_MIXER_H_