Support (E)AC3 passthrough

content/renderer/media/audio_renderer_mixer_manager.cc

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "content/renderer/media/audio_renderer_mixer_manager.h"
 
 #include <algorithm>
 #include <string>
 
 #include "base/bind.h"
@@ skipping 184 matching lines @@
     *device_status = device_info.device_status();
   if (device_info.device_status() != media::OUTPUT_DEVICE_STATUS_OK) {
     sink_cache_->ReleaseSink(sink.get());
     sink->Stop();
     return nullptr;
   }
 
   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.IsBitstreamFormat() ? input_params : mixer_output_params,

[chcunningham, 2017/06/14 20:03:08]

I would put this logic into GetMixerOutputParams. This will also make the
DVLOG(1) below correct. 

+      sink, base::Bind(LogMixerUmaHistogram, latency));
   AudioRendererMixerReference mixer_reference = {mixer, 1, sink.get()};
   mixers_[key] = mixer_reference;
   DVLOG(1) << __func__ << " mixer: " << mixer << " latency: " << latency
            << "\n input: " << input_params.AsHumanReadableString()
            << "\noutput: " << mixer_output_params.AsHumanReadableString();
   return mixer;
 }
 
 void AudioRendererMixerManager::ReturnMixer(media::AudioRendererMixer* mixer) {
   base::AutoLock auto_lock(mixers_lock_);
@@ skipping 31 matching lines @@
     const url::Origin& security_origin)
     : source_render_frame_id(source_render_frame_id),
       params(params),
       latency(latency),
       device_id(device_id),
       security_origin(security_origin) {}
 
 AudioRendererMixerManager::MixerKey::MixerKey(const MixerKey& other) = default;
 
 }  // namespace content