Resolves TSan v2 reports data races in voe_auto_test.

--- Note that I will add more fixes to this CL ---

BUG=1590

Review URL: https://webrtc-codereview.appspot.com/1286005

git-svn-id: http://webrtc.googlecode.com/svn/trunk@3770 4adac7df-926f-26a2-2b94-8c16560cd09d
diff --git a/webrtc/modules/audio_processing/audio_processing_impl.cc b/webrtc/modules/audio_processing/audio_processing_impl.cc
index 9051575..0c74893 100644
--- a/webrtc/modules/audio_processing/audio_processing_impl.cc
+++ b/webrtc/modules/audio_processing/audio_processing_impl.cc
@@ -209,6 +209,7 @@
 }
 
 int AudioProcessingImpl::sample_rate_hz() const {
+  CriticalSectionScoped crit_scoped(crit_);
   return sample_rate_hz_;
 }