Introduce media::AudioPushFifo and a couple of use cases (and clean-ups).

chrome/renderer/media/cast_receiver_audio_valve.cc

Index: chrome/renderer/media/cast_receiver_audio_valve.cc
diff --git a/chrome/renderer/media/cast_receiver_audio_valve.cc b/chrome/renderer/media/cast_receiver_audio_valve.cc
index 785d90df7e85c5f5acbbdb6afff9c06c16cc1759..5e47116fb602183ac4301068a3800de1a49cff18 100644
--- a/chrome/renderer/media/cast_receiver_audio_valve.cc
+++ b/chrome/renderer/media/cast_receiver_audio_valve.cc
@@ -4,26 +4,57 @@
 
 #include "chrome/renderer/media/cast_receiver_audio_valve.h"
 
+#include "base/bind.h"
+#include "base/bind_helpers.h"
+#include "base/time/time.h"
+#include "media/audio/audio_parameters.h"
+
 CastReceiverAudioValve::CastReceiverAudioValve(
+    const media::AudioParameters& params,
     media::AudioCapturerSource::CaptureCallback* cb)
-    : cb_(cb) {
+    : cb_(cb),
+      rechunker_(
+          base::TimeDelta::FromMicroseconds(params.frames_per_buffer() *
+                                            base::Time::kMicrosecondsPerSecond /
+                                            params.sample_rate()),
+          base::Bind(&CastReceiverAudioValve::DeliverRechunkedAudio,
+                     base::Unretained(this))) {
+  rechunker_.SetSampleRate(params.sample_rate());

[xjz, 2016/02/20 01:53:04]

Need to check returning true?

[miu, 2016/02/23 04:27:41]

No longer applicable.

 }
+
 CastReceiverAudioValve::~CastReceiverAudioValve() {}
 
-void CastReceiverAudioValve::Capture(const media::AudioBus* audio_source,
-                                     int audio_delay_milliseconds,
-                                     double volume,
-                                     bool key_pressed) {
-  base::AutoLock lock(lock_);
-  if (cb_) {
-    cb_->Capture(audio_source, audio_delay_milliseconds, volume, key_pressed);
-  }
+void CastReceiverAudioValve::DeliverDecodedAudio(
+    const media::AudioBus* audio_bus,
+    base::TimeTicks playout_time) {
+  const base::TimeDelta timestamp_relative_to_origin =
+      playout_time - base::TimeTicks();
+  // The following will result in zero, one, or multiple synchronous calls to
+  // DeliverRechunkedAudio().
+  rechunker_.Push(*audio_bus, timestamp_relative_to_origin);
 }
 
-void CastReceiverAudioValve::OnCaptureError(const std::string& message) {
+void CastReceiverAudioValve::DeliverRechunkedAudio(
+    const media::AudioBus& audio_bus,
+    base::TimeDelta timestamp_relative_to_origin) {
   base::AutoLock lock(lock_);
   if (cb_) {
-    cb_->OnCaptureError(message);
+    // The AudioCapturerSource::Callback interface provides timing information
+    // only as a relative delay value that means "captured N milliseconds ago."
+    // Therefore, translate the playout time to these semantics.  Since playout
+    // time is generally in the future, because audio should be decoded well
+    // ahead of when it should be played out, the audio delay value will
+    // generally be negative.
+    //
+    // TimeTicks::Now() is being called after the |lock_| was acquired in order
+    // to provide the most accurate delay value.
+    const base::TimeTicks playout_time =
+        base::TimeTicks() + timestamp_relative_to_origin;
+    const int audio_delay_milliseconds =
+        (base::TimeTicks::Now() - playout_time).InMilliseconds();
+
+    cb_->Capture(&audio_bus, audio_delay_milliseconds, 1.0 /* volume */,
+                 false /* key_pressed */);
   }
 }