Switch browser side audio capture path to use base time primitives.

media/audio/audio_io.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_AUDIO_AUDIO_IO_H_
 #define MEDIA_AUDIO_AUDIO_IO_H_
 
 #include <stdint.h>
 
 #include "base/time/time.h"
@@ skipping 101 matching lines @@
 };
 
 // Models an audio sink receiving recorded audio from the audio driver.
 class MEDIA_EXPORT AudioInputStream {
  public:
   class MEDIA_EXPORT AudioInputCallback {
    public:
     // Called by the audio recorder when a full packet of audio data is
     // available. This is called from a special audio thread and the
     // implementation should return as soon as possible.
-    // TODO(henrika): should be pure virtual when old OnData() is phased out.
     virtual void OnData(AudioInputStream* stream,
                         const AudioBus* source,
-                        uint32_t hardware_delay_bytes,
-                        double volume) {}
-
-    // TODO(henrika): don't use; to be removed.
-    virtual void OnData(AudioInputStream* stream,
-                        const uint8_t* src,
-                        uint32_t size,
-                        uint32_t hardware_delay_bytes,
-                        double volume) {}
+                        base::TimeDelta delay,

[o1ka, 2017/02/10 13:28:50]

Are we expecting that TimeTicks::IsHighResolution() is true on all the
platforms? Should we have a check somewhere for that?

+                        base::TimeTicks delay_timestamp,

[o1ka, 2017/02/10 13:28:50]

It's hard for me to interpret what "delay timestamp" means. What is it counted
from? Is it a "buffer timestamp"?

How is |delay| calculated? Is it a time interval between the moment the physical
signal is received and the moment OnData() is called? How the user should
interpret it?

Is  |delay_timestamp| - |delay| equal to the physical time of the signal?


Would be nice to have comments explaining the contract, and more descriptive
naming (maybe |latency| and |timestamp| will do?)

+                        double volume) = 0;
 
     // There was an error while recording audio. The audio sink cannot be
     // destroyed yet. No direct action needed by the AudioInputStream, but it
     // is a good place to stop accumulating sound data since is is likely that
     // recording will not continue.
     virtual void OnError(AudioInputStream* stream) = 0;
 
    protected:
     virtual ~AudioInputCallback() {}
   };
@@ skipping 33 matching lines @@
   // Returns the Automatic Gain Control (AGC) state.
   virtual bool GetAutomaticGainControl() = 0;
 
   // Returns the current muting state for the microphone.
   virtual bool IsMuted() = 0;
 };
 
 }  // namespace media
 
 #endif  // MEDIA_AUDIO_AUDIO_IO_H_