Add mute state field to AudioFrame.

webrtc/modules/audio_processing/audio_processing_impl_locking_unittest.cc

Index: webrtc/modules/audio_processing/audio_processing_impl_locking_unittest.cc
diff --git a/webrtc/modules/audio_processing/audio_processing_impl_locking_unittest.cc b/webrtc/modules/audio_processing/audio_processing_impl_locking_unittest.cc
index 28073558ec441e47e7d3996779e6f6c1e689beda..19d90fae113774390f1c4a3552ab892fb963b135 100644
--- a/webrtc/modules/audio_processing/audio_processing_impl_locking_unittest.cc
+++ b/webrtc/modules/audio_processing/audio_processing_impl_locking_unittest.cc
@@ -479,11 +479,12 @@ void PopulateAudioFrame(AudioFrame* frame,
                         RandomGenerator* rand_gen) {
   ASSERT_GT(amplitude, 0);
   ASSERT_LE(amplitude, 32767);
+  int16_t* frame_data = frame->mutable_data();
   for (size_t ch = 0; ch < frame->num_channels_; ch++) {
     for (size_t k = 0; k < frame->samples_per_channel_; k++) {
       // Store random 16 bit number between -(amplitude+1) and
       // amplitude.
-      frame->data_[k * ch] =
+      frame_data[k * ch] =
           rand_gen->RandInt(2 * amplitude + 1) - amplitude - 1;
     }
   }