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

media/audio/pulse/pulse_input.cc

Index: media/audio/pulse/pulse_input.cc
diff --git a/media/audio/pulse/pulse_input.cc b/media/audio/pulse/pulse_input.cc
index b27fb65694c61669d67675bc1debcbe15f035550..5a5750a949e8e3eca8e166ade91f3796e5686bf9 100644
--- a/media/audio/pulse/pulse_input.cc
+++ b/media/audio/pulse/pulse_input.cc
@@ -270,8 +270,7 @@ void PulseAudioInputStream::StreamNotifyCallback(pa_stream* s,
 }
 
 void PulseAudioInputStream::ReadData() {
-  uint32_t hardware_delay = pulse::GetHardwareLatencyInBytes(
-      handle_, params_.sample_rate(), params_.GetBytesPerFrame());
+  base::TimeDelta hardware_delay = pulse::GetHardwareLatency(handle_);
 
   // Update the AGC volume level once every second. Note that,
   // |volume| is also updated each time SetVolume() is called
@@ -309,8 +308,11 @@ void PulseAudioInputStream::ReadData() {
     const AudioBus* audio_bus = fifo_.Consume();
 
     // Compensate the audio delay caused by the FIFO.
-    hardware_delay += fifo_.GetAvailableFrames() * params_.GetBytesPerFrame();
-    callback_->OnData(this, audio_bus, hardware_delay, normalized_volume);
+    hardware_delay += base::TimeDelta::FromSecondsD(
+        fifo_.GetAvailableFrames() /
+        static_cast<double>(params_.sample_rate()));

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

I'm not sure if this is a good enough approximation, if each fifo Push() has a
different latency.

And I don't really understand if and how pulse::GetHardwareLatency() and/or
other calculations take into account Sleep() call at l.320.

Comments would be very helpful.

[DaleCurtis, 2017/02/11 01:43:13]

It's a good question, the answer is they don't. I've moved them inside the loop
so they are correctly compensating. Probably this code can be removed now that
we have a circular buffer at the process boundary.

+    callback_->OnData(this, audio_bus, hardware_delay, base::TimeTicks::Now(),
+                      normalized_volume);
 
     // Sleep 5ms to wait until render consumes the data in order to avoid
     // back to back OnData() method.