Fix latency plumbing in media::VirtualAudio[Input|Output]Stream.

media/audio/virtual_audio_output_stream.cc

Index: media/audio/virtual_audio_output_stream.cc
diff --git a/media/audio/virtual_audio_output_stream.cc b/media/audio/virtual_audio_output_stream.cc
index 016c2f331b32e13ec1db8acab47d615405df6949..29e3804fe21daa3d6488b8aa80b5463cbc796db0 100644
--- a/media/audio/virtual_audio_output_stream.cc
+++ b/media/audio/virtual_audio_output_stream.cc
@@ -77,7 +77,12 @@ double VirtualAudioOutputStream::ProvideInput(AudioBus* audio_bus,
   // platform.
   DCHECK(callback_);
 
-  const int frames = callback_->OnMoreData(audio_bus, 0);
+  DCHECK_GE(buffer_delay, base::TimeDelta());
+  const int64 upstream_delay_in_bytes =
+      params_.GetBytesPerSecond() * buffer_delay /
+          base::TimeDelta::FromSeconds(1);
+  const int frames = callback_->OnMoreData(
+      audio_bus, static_cast<uint32>(upstream_delay_in_bytes));

[hubbe, 2014/12/01 21:56:46]

Is this allowed to not be a multiple of channels*bytes_per_sample?

[miu, 2014/12/02 00:02:44]

The call to GetBytesPerSecond() ensures this, since it will be a multiple of
that expression.

BTW--The "bytes delay" interface is poor (agreed by multiple owners), to be
replaced by a TimeDelta (probably).  There's a bug open for this.

   if (frames < audio_bus->frames())
     audio_bus->ZeroFramesPartial(frames, audio_bus->frames() - frames);