Improved AGC update scheme for the audio backend in Chrome

media/audio/linux/alsa_input.cc

Index: media/audio/linux/alsa_input.cc
diff --git a/media/audio/linux/alsa_input.cc b/media/audio/linux/alsa_input.cc
index 8f785301bf9ee2fb52f223dc45b53e2ff48038e9..ce337d335cb3983368929edae4118253b10c26e6 100644
--- a/media/audio/linux/alsa_input.cc
+++ b/media/audio/linux/alsa_input.cc
@@ -102,6 +102,7 @@ bool AlsaPcmInputStream::Open() {
 void AlsaPcmInputStream::Start(AudioInputCallback* callback) {
   DCHECK(!callback_ && callback);
   callback_ = callback;
+  StartAgc();
   int error = wrapper_->PcmPrepare(device_handle_);
   if (error < 0) {
     HandleError("PcmPrepare", error);
@@ -203,7 +204,7 @@ void AlsaPcmInputStream::ReadAudio() {
   // 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(&normalized_volume);
+  GetAgcVolume(&normalized_volume);
 
   while (num_buffers--) {
     int frames_read = wrapper_->PcmReadi(device_handle_, audio_buffer_.get(),
@@ -240,6 +241,8 @@ void AlsaPcmInputStream::Stop() {
   if (!device_handle_ || !callback_)
     return;
 
+  StopAgc();
+
   // Stop is always called before Close. In case of error, this will be
   // also called when closing the input controller.
   audio_manager_->DecreaseActiveInputStreamCount();