Add new files for VideoSourceBase to roll into Chrome in preparation for implementatin.

webrtc/media/media.gyp

 # Copyright (c) 2016 The WebRTC project authors. All Rights Reserved.
 #
 # Use of this source code is governed by a BSD-style license
 # that can be found in the LICENSE file in the root of the source
 # tree. An additional intellectual property rights grant can be found
 # in the file PATENTS.  All contributing project authors may
 # be found in the AUTHORS file in the root of the source tree.
 
 {
   'includes': [ '../build/common.gypi', ],
@@ skipping 56 matching lines @@
         'base/videocapturer.cc',
         'base/videocapturer.h',
         'base/videocapturerfactory.h',
         'base/videocommon.cc',
         'base/videocommon.h',
         'base/videoframe.cc',
         'base/videoframe.h',
         'base/videoframefactory.cc',
         'base/videoframefactory.h',
         'base/videorenderer.h',
+        'base/videosourcebase.cc',
+        'base/videosourcebase.h',
         'base/yuvframegenerator.cc',
         'base/yuvframegenerator.h',
         'devices/deviceinfo.h',
         'devices/videorendererfactory.h',
         'engine/nullwebrtcvideoengine.h',
         'engine/simulcast.cc',
         'engine/simulcast.h',
         'engine/webrtccommon.h',
         'engine/webrtcmediaengine.cc',
         'engine/webrtcmediaengine.h',
@@ skipping 205 matching lines @@
         }],
         ['OS=="android" and include_internal_device_management==1', {
           'sources': [
             'devices/mobiledevicemanager.cc',
           ],
         }],
       ],
     },  # target rtc_media
   ],  # targets.
 }