Less lock acquisitions for AudioMixer.

webrtc/modules/audio_mixer/test/audio_mixer_unittest.cc

Index: webrtc/modules/audio_mixer/test/audio_mixer_unittest.cc
diff --git a/webrtc/modules/audio_mixer/test/audio_mixer_unittest.cc b/webrtc/modules/audio_mixer/test/audio_mixer_unittest.cc
index 36bd7c4211e6a9fc0398dfebe3773b91e69a4a1b..5a9bc27e2c2a716d418cedb11a2ed19dff8753a0 100644
--- a/webrtc/modules/audio_mixer/test/audio_mixer_unittest.cc
+++ b/webrtc/modules/audio_mixer/test/audio_mixer_unittest.cc
@@ -212,6 +212,8 @@ TEST(AudioMixer, ParticipantSampleRate) {
   for (auto frequency : {8000, 16000, 32000, 48000}) {
     EXPECT_CALL(participant, GetAudioFrameWithMuted(_, frequency))
         .Times(Exactly(1));
+    participant.fake_frame()->sample_rate_hz_ = frequency;
+    participant.fake_frame()->samples_per_channel_ = frequency / 100;

[aleloi, 2016/08/30 15:13:34]

There are now RTC_DCHECKs for receiving correct rate and
samples/channel from audio sources.

     mixer->Mix(frequency, 1, &frame_for_mixing);
     EXPECT_EQ(frequency, frame_for_mixing.sample_rate_hz_);
   }