MediaStream audio: Refactor 3 separate "glue" implementations into one.

content/content_renderer.gypi

Index: content/content_renderer.gypi
diff --git a/content/content_renderer.gypi b/content/content_renderer.gypi
index ca82da8fdb279d1de1c4202e04efb3987018f1a7..0548986c9eed9ff5c329eafbbcd25ff444304c8f 100644
--- a/content/content_renderer.gypi
+++ b/content/content_renderer.gypi
@@ -313,10 +313,14 @@
       'renderer/media/cdm/ppapi_decryptor.h',
       'renderer/media/cdm/render_cdm_factory.cc',
       'renderer/media/cdm/render_cdm_factory.h',
+      'renderer/media/external_media_stream_audio_source.cc',
+      'renderer/media/external_media_stream_audio_source.h',
       'renderer/media/media_permission_dispatcher.cc',
       'renderer/media/media_permission_dispatcher.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',
@@ -350,6 +354,8 @@
       'renderer/media/video_capture_impl_manager.h',
       'renderer/media/video_capture_message_filter.cc',
       'renderer/media/video_capture_message_filter.h',
+      'renderer/media/webaudio_media_stream_source.cc',
+      'renderer/media/webaudio_media_stream_source.h',
       'renderer/media/webmediaplayer_ms.cc',
       'renderer/media/webmediaplayer_ms.h',
       'renderer/media/webmediaplayer_ms_compositor.cc',
@@ -657,11 +663,6 @@
       'renderer/media/media_stream_audio_processor.h',
       'renderer/media/media_stream_audio_processor_options.cc',
       'renderer/media/media_stream_audio_processor_options.h',
-      'renderer/media/media_stream_audio_sink_owner.cc',
-      'renderer/media/media_stream_audio_sink_owner.h',
-      'renderer/media/media_stream_audio_source.cc',
-      'renderer/media/media_stream_audio_source.h',
-      'renderer/media/media_stream_audio_track_sink.h',
       'renderer/media/media_stream_center.cc',
       'renderer/media/media_stream_dispatcher.cc',
       'renderer/media/media_stream_registry_interface.h',
@@ -708,10 +709,6 @@
       'renderer/media/video_track_adapter.h',
       'renderer/media/video_track_recorder.cc',
       'renderer/media/video_track_recorder.h',
-      'renderer/media/webaudio_capturer_source.cc',
-      'renderer/media/webaudio_capturer_source.h',
-      'renderer/media/webrtc/media_stream_remote_audio_track.cc',
-      'renderer/media/webrtc/media_stream_remote_audio_track.h',
       'renderer/media/webrtc/media_stream_remote_video_source.cc',
       'renderer/media/webrtc/media_stream_remote_video_source.h',
       'renderer/media/webrtc/media_stream_track_metrics.cc',
@@ -720,6 +717,12 @@
       'renderer/media/webrtc/media_stream_video_webrtc_sink.h',
       'renderer/media/webrtc/peer_connection_dependency_factory.cc',
       'renderer/media/webrtc/peer_connection_dependency_factory.h',
+      'renderer/media/webrtc/peer_connection_remote_audio_source.cc',
+      'renderer/media/webrtc/peer_connection_remote_audio_source.h',
+      'renderer/media/webrtc/processed_local_audio_source.cc',
+      'renderer/media/webrtc/processed_local_audio_source.h',
+      'renderer/media/webrtc/processed_local_audio_track.cc',
+      'renderer/media/webrtc/processed_local_audio_track.h',
       'renderer/media/webrtc/stun_field_trial.cc',
       'renderer/media/webrtc/stun_field_trial.h',
       'renderer/media/webrtc/track_observer.cc',
@@ -734,8 +737,6 @@
       'renderer/media/webrtc/webrtc_video_capturer_adapter.h',
       'renderer/media/webrtc/webrtc_video_frame_adapter.cc',
       'renderer/media/webrtc/webrtc_video_frame_adapter.h',
-      'renderer/media/webrtc_audio_capturer.cc',
-      'renderer/media/webrtc_audio_capturer.h',
       'renderer/media/webrtc_audio_device_impl.cc',
       'renderer/media/webrtc_audio_device_impl.h',
       'renderer/media/webrtc_audio_device_not_impl.cc',
@@ -746,8 +747,6 @@
       'renderer/media/webrtc_identity_service.h',
       'renderer/media/webrtc_local_audio_source_provider.cc',
       'renderer/media/webrtc_local_audio_source_provider.h',
-      'renderer/media/webrtc_local_audio_track.cc',
-      'renderer/media/webrtc_local_audio_track.h',
       'renderer/media/webrtc_logging.cc',
       'renderer/media/webrtc_logging.h',
       'renderer/media/webrtc_uma_histograms.cc',