Add Config option to enable 48kHz support in AudioProcessing

BUG=webrtc:3146
R=andrew@webrtc.org, bjornv@webrtc.org

Review URL: https://webrtc-codereview.appspot.com/45389004

Cr-Commit-Position: refs/heads/master@{#8563}
git-svn-id: http://webrtc.googlecode.com/svn/trunk@8563 4adac7df-926f-26a2-2b94-8c16560cd09d

webrtc/modules/audio_processing/audio_processing_impl.h

@@ -222,6 +222,8 @@ class AudioProcessingImpl : public AudioProcessing {
   const bool beamformer_enabled_;
   rtc::scoped_ptr<Beamformer> beamformer_;
   const std::vector<Point> array_geometry_;
+
+  const bool supports_48kHz_;
 };
 
 }  // namespace webrtc