Pass delay and timestamp to AudioSourceCallback::OnMoreData.

media/audio/audio_output_controller.cc

Index: media/audio/audio_output_controller.cc
diff --git a/media/audio/audio_output_controller.cc b/media/audio/audio_output_controller.cc
index 9b8f52387d8e7a4f638d73c7d1127ae2a2f394e2..3fe8db0ea6c299e35f5b25c2b4d44d1b8b5ec2f4 100644
--- a/media/audio/audio_output_controller.cc
+++ b/media/audio/audio_output_controller.cc
@@ -6,6 +6,7 @@
 
 #include <stdint.h>
 
+#include <algorithm>
 #include <limits>
 
 #include "base/bind.h"
@@ -292,9 +293,9 @@ void AudioOutputController::DoReportError() {
     handler_->OnError();
 }
 
-int AudioOutputController::OnMoreData(AudioBus* dest,
-                                      uint32_t total_bytes_delay,
-                                      uint32_t frames_skipped) {
+int AudioOutputController::OnMoreData(base::TimeTicks target_playout_time,
+                                      int prior_frames_skipped,
+                                      AudioBus* dest) {
   TRACE_EVENT0("audio", "AudioOutputController::OnMoreData");
 
   // Indicate that we haven't wedged (at least not indefinitely, WedgeCheck()
@@ -306,9 +307,13 @@ int AudioOutputController::OnMoreData(AudioBus* dest,
 
   sync_reader_->Read(dest);
 
+  const base::TimeDelta delay =

[chcunningham, 2016/08/27 00:36:18]

Can you add a comment explaining why this guard is needed. Something like the
explanation you already gave in the CL discussion is great.

[miu, 2016/08/31 23:26:54]

Looks like this API change should propagate through the IPC interface. If you're
not going to tackle that in this CL, can you put a TODO comment here and file a
bug at crbug.com for tracking purposes?

BTW--If we fix the IPC interface, there would be no reason to call
TimeTicks::Now() at all. ;-)

[jameswest, 2016/09/07 21:52:16]

When the number of bytes is passed to UpdatePendingBytes, where does that
ultimately go? I see it gets sent to a SyncSocket in AudioSyncReader, but I
can't figure out where that goes.

[miu, 2016/09/07 22:19:36]

The consumer is media::AudioDeviceThread:
https://cs.chromium.org/chromium/src/media/audio/audio_device_thread.cc?rcl=1...

That's a real-time thread, and when it calls callback_->Process(), the
implementation in media::AudioOutputDevice is invoked:
https://cs.chromium.org/chromium/src/media/audio/audio_output_device.cc?rcl=0...

From there, AudioOutputDevice calls AudioRendererSink::Render(), which should be
changed to identically match the OnMoreData() API:
https://cs.chromium.org/chromium/src/media/base/audio_renderer_sink.h?rcl=147...

It's up to you whether you want to do these things. On the one hand, they really
are needed now (by https://codereview.chromium.org/2060833002/), and I'm sure
Mikhail would really appreciate you doing the work since, otherwise, he'd have
to. On the other hand, changing the AudioRendererSink interface would require
tweaking the audio handling code in about 10-15 other classes, and so it's not
just a quick thing for you.

[James West, 2016/09/13 07:40:50]

I'm happy to do this, but I think it should be a separate change to avoid
greatly expanding the size of this one. I added a TODO.

[miu, 2016/09/16 18:35:58]

SGTM.

+      std::max(target_playout_time - base::TimeTicks::Now(), base::TimeDelta());
+  const int total_bytes_delay = delay.InSeconds() * params_.GetBytesPerSecond();

[miu, 2016/08/31 23:26:54]

s/InSeconds/InSecondsF/ to prevent serious loss of precision!

[James West, 2016/09/13 07:40:50]

Done.

   const int frames = dest->frames();
   sync_reader_->UpdatePendingBytes(
-      total_bytes_delay + frames * params_.GetBytesPerFrame(), frames_skipped);
+      total_bytes_delay + frames * params_.GetBytesPerFrame(),
+      prior_frames_skipped);
 
   bool need_to_duplicate = false;
   {
@@ -316,17 +321,12 @@ int AudioOutputController::OnMoreData(AudioBus* dest,
     need_to_duplicate = !duplication_targets_.empty();
   }
   if (need_to_duplicate) {
-    const base::TimeTicks reference_time =
-        base::TimeTicks::Now() +
-        base::TimeDelta::FromMicroseconds(base::Time::kMicrosecondsPerSecond *
-                                          total_bytes_delay /
-                                          params_.GetBytesPerSecond());
     std::unique_ptr<AudioBus> copy(AudioBus::Create(params_));
     dest->CopyTo(copy.get());
     message_loop_->PostTask(
         FROM_HERE,
         base::Bind(&AudioOutputController::BroadcastDataToDuplicationTargets,
-                   this, base::Passed(&copy), reference_time));
+                   this, base::Passed(&copy), target_playout_time));
   }
 
   if (will_monitor_audio_levels())