Add support for unmixed audio from remote WebRTC remote tracks.

content/renderer/BUILD.gn

 # Copyright 2014 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.
 
 import("//build/config/features.gni")
 import("//build/config/ui.gni")
 import("//content/renderer/renderer.gni")
 import("//media/media_options.gni")
 
 source_set("renderer") {
@@ skipping 109 matching lines @@
     ]
   }
 
   # TODO(jrg): remove the OS=="android" section?
   # http://crbug.com/113172
   # Understand better how media_stream_ is tied into Chromium.
   if (!enable_webrtc && is_android) {
     sources -= [
       "media/media_stream_audio_level_calculator.cc",
       "media/media_stream_audio_level_calculator.h",
+      "media/media_stream_audio_track.cc",
+      "media/media_stream_audio_track.h",
       "media/media_stream_center.h",
       "media/media_stream_constraints_util.cc",
       "media/media_stream_constraints_util.h",
       "media/media_stream_dispatcher.h",
       "media/media_stream_dispatcher_eventhandler.h",
       "media/media_stream_track.cc",
       "media/media_stream_track.h",
     ]
   }
 
@@ skipping 72 matching lines @@
       "vr/vr_dispatcher.h",
       "vr/vr_type_converters.cc",
       "vr/vr_type_converters.h",
     ]
   }
 
   if (use_seccomp_bpf) {
     defines += [ "USE_SECCOMP_BPF" ]
   }
 }