Improved AGC update scheme for the audio backend in Chrome.

This CL serves two purposes:

1) Improve the existing "mic-volume-checking"-scheme by ensuring that we no longer calls native audio functions from the core capture thread.
2) Prepare for adding AGC to the live-audio backend.

TBR=tommi@chromium.org
BUG=none
TEST=WebRTC loopback tests in Chrome where I monitor the microphone volume while speaking into the mic.

Review URL: https://codereview.chromium.org/15563004

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@202538 0039d316-1c4b-4281-b951-d872f2087c98

2 files changed, 8 insertions, 5 deletions

diff --git a/media/audio/pulse/pulse_input.cc b/media/audio/pulse/pulse_input.cc
index 4e48e10..c365c47 100644
--- a/media/audio/pulse/pulse_input.cc
+++ b/media/audio/pulse/pulse_input.cc
@@ -66,6 +66,8 @@ void PulseAudioInputStream::Start(AudioInputCallback* callback) {
   if (stream_started_)
     return;
 
+  StartAgc();
+
   // Clean up the old buffer.
   pa_stream_drop(handle_);
   buffer_->Clear();
@@ -86,6 +88,8 @@ void PulseAudioInputStream::Stop() {
   if (!stream_started_)
     return;
 
+  StopAgc();
+
   // Set the flag to false to stop filling new data to soundcard.
   stream_started_ = false;
 
@@ -246,11 +250,10 @@ void PulseAudioInputStream::ReadData() {
   // Update the AGC volume level once every second. Note that,
   // |volume| is also updated each time SetVolume() is called
   // through IPC by the render-side AGC.
-  // QueryAgcVolume() will trigger a callback to asynchronously update the
-  // |volume_|, we disregard the |normalized_volume| from QueryAgcVolume()
+  // We disregard the |normalized_volume| from GetAgcVolume()
   // and use the value calculated by |volume_|.
   double normalized_volume = 0.0;
-  QueryAgcVolume(&normalized_volume);
+  GetAgcVolume(&normalized_volume);
   normalized_volume = volume_ / GetMaxVolume();
 
   do {
diff --git a/media/audio/pulse/pulse_input.h b/media/audio/pulse/pulse_input.h
index 00bc03f..7566eac 100644
--- a/media/audio/pulse/pulse_input.h
+++ b/media/audio/pulse/pulse_input.h
@@ -8,8 +8,8 @@
 #include <string>
 
 #include "base/threading/thread_checker.h"
+#include "media/audio/agc_audio_stream.h"
 #include "media/audio/audio_device_name.h"
-#include "media/audio/audio_input_stream_impl.h"
 #include "media/audio/audio_io.h"
 #include "media/audio/audio_parameters.h"
 
@@ -23,7 +23,7 @@ namespace media {
 class AudioManagerPulse;
 class SeekableBuffer;
 
-class PulseAudioInputStream : public AudioInputStreamImpl {
+class PulseAudioInputStream : public AgcAudioStream<AudioInputStream> {
  public:
   PulseAudioInputStream(AudioManagerPulse* audio_manager,
                         const std::string& device_name,