Support (E)AC3 passthrough

content/renderer/media/audio_renderer_mixer_manager.cc

Index: content/renderer/media/audio_renderer_mixer_manager.cc
diff --git a/content/renderer/media/audio_renderer_mixer_manager.cc b/content/renderer/media/audio_renderer_mixer_manager.cc
index f22bdc3f6d7c94d38cff3ee3f6ac4e05466c47ac..315c867c04bc72b36bd683e12f34ba43e60fca7c 100644
--- a/content/renderer/media/audio_renderer_mixer_manager.cc
+++ b/content/renderer/media/audio_renderer_mixer_manager.cc
@@ -202,7 +202,8 @@ media::AudioRendererMixer* AudioRendererMixerManager::GetMixer(
   const media::AudioParameters& mixer_output_params =
       GetMixerOutputParams(input_params, device_info.output_params(), latency);
   media::AudioRendererMixer* mixer = new media::AudioRendererMixer(
-      mixer_output_params, sink, base::Bind(LogMixerUmaHistogram, latency));
+      input_params.IsRawFormat() ? input_params : mixer_output_params, sink,
+      base::Bind(LogMixerUmaHistogram, latency));
   AudioRendererMixerReference mixer_reference = {mixer, 1, sink.get()};
   mixers_[key] = mixer_reference;
   DVLOG(1) << __func__ << " mixer: " << mixer << " latency: " << latency