Use LocalMediaStreamAudioSource for screen-casting use cases.

content/content_renderer.gypi

 # 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.
 
 {
   'dependencies': [
     '../base/base.gyp:base',
     '../base/third_party/dynamic_annotations/dynamic_annotations.gyp:dynamic_annotations',
     '../cc/cc.gyp:cc',
     '../cc/cc.gyp:cc_proto',
@@ skipping 298 matching lines @@
       'renderer/media/cdm/pepper_cdm_wrapper_impl.cc',
       'renderer/media/cdm/pepper_cdm_wrapper_impl.h',
       'renderer/media/cdm/ppapi_decryptor.cc',
       'renderer/media/cdm/ppapi_decryptor.h',
       'renderer/media/cdm/render_cdm_factory.cc',
       'renderer/media/cdm/render_cdm_factory.h',
       'renderer/media/html_audio_element_capturer_source.cc',
       'renderer/media/html_audio_element_capturer_source.h',
       'renderer/media/external_media_stream_audio_source.cc',
       'renderer/media/external_media_stream_audio_source.h',
+      'renderer/media/local_media_stream_audio_source.cc',
+      'renderer/media/local_media_stream_audio_source.h',
       'renderer/media/media_permission_dispatcher.cc',
       'renderer/media/media_permission_dispatcher.h',
       'renderer/media/media_stream_audio_deliverer.h',
       'renderer/media/media_stream_audio_level_calculator.cc',
       'renderer/media/media_stream_audio_level_calculator.h',
       'renderer/media/media_stream_audio_source.cc',
       'renderer/media/media_stream_audio_source.h',
       'renderer/media/media_stream_audio_track.cc',
       'renderer/media/media_stream_audio_track.h',
       'renderer/media/media_stream_center.h',
@@ skipping 576 matching lines @@
     }],
   ],
   'target_conditions': [
     ['OS=="android"', {
       'sources/': [
         ['include', '^renderer/render_view_linux\\.cc$'],
       ],
     }],
   ],
 }