Switch audio synchronization from sleep() based to select() based.

media/audio/audio_parameters.cc

Index: media/audio/audio_parameters.cc
diff --git a/media/audio/audio_parameters.cc b/media/audio/audio_parameters.cc
index 5e77c60cb94484a4db36cba14f31c84a994fd3c0..b7ea4870c23c2bf5f6b51c2bfbfaa5279c566ef1 100644
--- a/media/audio/audio_parameters.cc
+++ b/media/audio/audio_parameters.cc
@@ -89,6 +89,12 @@ int AudioParameters::GetBytesPerFrame() const {
   return channels_ * bits_per_sample_ / 8;
 }
 
+base::TimeDelta AudioParameters::GetBufferDuration() const {
+  return base::TimeDelta::FromMicroseconds(
+      frames_per_buffer_ * base::Time::kMicrosecondsPerSecond /
+      static_cast<float>(sample_rate_));
+}
+
 void AudioParameters::SetDiscreteChannels(int channels) {
   channel_layout_ = CHANNEL_LAYOUT_DISCRETE;
   channels_ = channels;