Added code for MediaStreamAudioTrackProcessing Finch Experiment enabling

content/renderer/media/media_stream_audio_processor.cc

 // Copyright 2013 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/media_stream_audio_processor.h"
 
 #include "base/command_line.h"
 #include "base/debug/trace_event.h"
+#include "base/metrics/field_trial.h"
 #include "content/public/common/content_switches.h"
 #include "content/renderer/media/media_stream_audio_processor_options.h"
 #include "content/renderer/media/rtc_media_constraints.h"
 #include "media/audio/audio_parameters.h"
 #include "media/base/audio_converter.h"
 #include "media/base/audio_fifo.h"
 #include "media/base/channel_layout.h"
 #include "third_party/WebKit/public/platform/WebMediaConstraints.h"
 #include "third_party/libjingle/source/talk/app/webrtc/mediaconstraintsinterface.h"
 #include "third_party/webrtc/modules/audio_processing/typing_detection.h"
@@ skipping 238 matching lines @@
 void MediaStreamAudioProcessor::GetStats(AudioProcessorStats* stats) {
   stats->typing_noise_detected =
       (base::subtle::Acquire_Load(&typing_detected_) != false);
   GetAecStats(audio_processing_.get(), stats);
 }
 
 void MediaStreamAudioProcessor::InitializeAudioProcessingModule(
     const blink::WebMediaConstraints& constraints, int effects,
     MediaStreamType type) {
   DCHECK(!audio_processing_);
+  const std::string group_name =
+      base::FieldTrialList::FindFullName("MediaStreamAudioTrackProcessing");
   if (!CommandLine::ForCurrentProcess()->HasSwitch(
-          switches::kEnableAudioTrackProcessing)) {
+          switches::kEnableAudioTrackProcessing) &&
+      group_name != "Enabled") {
     return;
   }
 
   RTCMediaConstraints native_constraints(constraints);
 
   // Only apply the fixed constraints for gUM of MEDIA_DEVICE_AUDIO_CAPTURE.
   DCHECK(IsAudioMediaType(type));
   if (type == MEDIA_DEVICE_AUDIO_CAPTURE)
     ApplyFixedAudioConstraints(&native_constraints);
 
@@ skipping 203 matching lines @@
 
   StopAecDump();
 
   if (playout_data_source_)
     playout_data_source_->RemovePlayoutSink(this);
 
   audio_processing_.reset();
 }
 
 }  // namespace content