Fix data race in AMP.

webrtc/modules/audio_processing/audio_processing_impl.cc

Index: webrtc/modules/audio_processing/audio_processing_impl.cc
diff --git a/webrtc/modules/audio_processing/audio_processing_impl.cc b/webrtc/modules/audio_processing/audio_processing_impl.cc
index bbfb771182cc7196f0e8e0ca9fb63860617d6b8f..81d6c70be9131a4a3e263f6738e95369acdd3327 100644
--- a/webrtc/modules/audio_processing/audio_processing_impl.cc
+++ b/webrtc/modules/audio_processing/audio_processing_impl.cc
@@ -489,6 +489,7 @@ int AudioProcessingImpl::ProcessStream(const float* const* src,
                                        int output_sample_rate_hz,
                                        ChannelLayout output_layout,
                                        float* const* dest) {
+  CriticalSectionScoped crit_scoped(crit_);

[Andrew MacDonald, 2015/08/11 18:56:36]

FYI: Looks like the webrtc mutexes are recursive, but it's still not great to be
locking this here and in the ProcessStream call below. I think it's OK since we
intend to remove this call.

   StreamConfig input_stream = api_format_.input_stream();
   input_stream.set_sample_rate_hz(input_sample_rate_hz);
   input_stream.set_num_channels(ChannelsFromLayout(input_layout));