Improved AGC update scheme for the audio backend in Chrome

media/audio/linux/alsa_input.h

Index: media/audio/linux/alsa_input.h
diff --git a/media/audio/linux/alsa_input.h b/media/audio/linux/alsa_input.h
index df2b47104b60c8bf68ee480a45a83e5952dfe03d..57092ebb0cf40319c7d338f936439b5669322e2b 100644
--- a/media/audio/linux/alsa_input.h
+++ b/media/audio/linux/alsa_input.h
@@ -13,7 +13,7 @@
 #include "base/memory/scoped_ptr.h"
 #include "base/memory/weak_ptr.h"
 #include "base/time.h"
-#include "media/audio/audio_input_stream_impl.h"
+#include "media/audio/agc_audio_stream.h"
 #include "media/audio/audio_io.h"
 #include "media/audio/audio_parameters.h"
 
@@ -25,7 +25,7 @@ class AudioManagerLinux;
 // Provides an input stream for audio capture based on the ALSA PCM interface.
 // This object is not thread safe and all methods should be invoked in the
 // thread that created the object.
-class AlsaPcmInputStream : public AudioInputStreamImpl {
+class AlsaPcmInputStream : public AgcAudioStream<AudioInputStream> {
  public:
   // Pass this to the constructor if you want to attempt auto-selection
   // of the audio recording device.