Enable renderer-side mixing output of different audio sources basing on finch

content/renderer/media/audio_device_factory.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_device_factory.h"
 
 #include <algorithm>
 
 #include "base/logging.h"
 #include "content/common/content_constants_internal.h"
 #include "content/renderer/media/audio_input_message_filter.h"
 #include "content/renderer/media/audio_message_filter.h"
 #include "content/renderer/media/audio_renderer_mixer_manager.h"
 #include "content/renderer/render_thread_impl.h"
 #include "media/audio/audio_input_device.h"
 #include "media/audio/audio_output_device.h"
 #include "media/base/audio_renderer_mixer_input.h"
+#include "media/base/media_switches.h"
 #include "url/origin.h"
 
 namespace content {
 
 // static
 AudioDeviceFactory* AudioDeviceFactory::factory_ = NULL;
 
 namespace {
 const int64_t kMaxAuthorizationTimeoutMs = 4000;
 
@@ skipping 13 matching lines @@
   device->RequestDeviceAuthorization();
   return device;
 }
 
 // This is where we decide which audio will go to mixers and which one to
 // AudioOutpuDevice directly.
 bool IsMixable(AudioDeviceFactory::SourceType source_type) {
   if (source_type == AudioDeviceFactory::kSourceMediaElement)
     return true;  // Must ALWAYS go through mixer.
 
-  // TODO(olka): make a decision for the rest of the sources basing on OS
-  // type and configuration parameters.
-  return false;
+  // Mix everything if experiment is enabled; otherwise mix nothing else.
+  return base::FeatureList::IsEnabled(media::kNewAudioRenderingMixingStrategy);
 }
 
 scoped_refptr<media::SwitchableAudioRendererSink> NewMixableSink(
     int render_frame_id,
     int session_id,
     const std::string& device_id,
     const url::Origin& security_origin) {
   RenderThreadImpl* render_thread = RenderThreadImpl::current();
   return scoped_refptr<media::AudioRendererMixerInput>(
       render_thread->GetAudioRendererMixerManager()->CreateInput(
@@ skipping 113 matching lines @@
                                                device_id, security_origin);
     if (sink)
       return sink;
   }
 
   return NewOutputDevice(render_frame_id, session_id, device_id,
                          security_origin);
 }
 
 }  // namespace content