Restore sample_rate_hz() until Chromium is updated to not use it.

TBR=bjornv
TESTED=Chromium builds against webrtc head.
BUG=2894

Review URL: https://webrtc-codereview.appspot.com/12349004

git-svn-id: http://webrtc.googlecode.com/svn/trunk@5962 4adac7df-926f-26a2-2b94-8c16560cd09d
diff --git a/webrtc/modules/audio_processing/audio_processing_impl.h b/webrtc/modules/audio_processing/audio_processing_impl.h
index 3a0ad24..d34f305 100644
--- a/webrtc/modules/audio_processing/audio_processing_impl.h
+++ b/webrtc/modules/audio_processing/audio_processing_impl.h
@@ -98,6 +98,7 @@
   }
   virtual int set_sample_rate_hz(int rate) OVERRIDE;
   virtual int input_sample_rate_hz() const OVERRIDE;
+  virtual int sample_rate_hz() const OVERRIDE;
   virtual int proc_sample_rate_hz() const OVERRIDE;
   virtual int proc_split_sample_rate_hz() const OVERRIDE;
   virtual int num_input_channels() const OVERRIDE;