Add Config struct for experimental AGC.

Disable in the audio mixer.

TBR=aluebs,bjornv
BUG=2844

Review URL: https://webrtc-codereview.appspot.com/7769004

git-svn-id: http://webrtc.googlecode.com/svn/trunk@5454 4adac7df-926f-26a2-2b94-8c16560cd09d
diff --git a/webrtc/modules/audio_processing/include/audio_processing.h b/webrtc/modules/audio_processing/include/audio_processing.h
index edb9962..cdbadb9 100644
--- a/webrtc/modules/audio_processing/include/audio_processing.h
+++ b/webrtc/modules/audio_processing/include/audio_processing.h
@@ -50,8 +50,15 @@
 //   except when really necessary.
 struct DelayCorrection {
   DelayCorrection() : enabled(false) {}
-  DelayCorrection(bool enabled) : enabled(enabled) {}
+  explicit DelayCorrection(bool enabled) : enabled(enabled) {}
+  bool enabled;
+};
 
+// Must be provided through AudioProcessing::Create(Confg&). It will have no
+// impact if used with AudioProcessing::SetExtraOptions().
+struct ExperimentalAgc {
+  ExperimentalAgc() : enabled(true) {}
+  explicit ExperimentalAgc(bool enabled) : enabled(enabled) {}
   bool enabled;
 };