Extract simulcast rate allocation outside of video encoder.

webrtc/modules/video_coding/utility/video_coding_utility.gyp

 # Copyright (c) 2013 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': [
@@ skipping 12 matching lines @@
         'frame_dropper.h',
         'h264_bitstream_parser.cc',
         'h264_bitstream_parser.h',
         'ivf_file_writer.cc',
         'ivf_file_writer.h',
         'moving_average.h',
         'qp_parser.cc',
         'qp_parser.h',
         'quality_scaler.cc',
         'quality_scaler.h',
+        'simulcast_rate_allocator.cc',
+        'simulcast_rate_allocator.h',
         'vp8_header_parser.cc',
         'vp8_header_parser.h',
       ],
     },
   ], # targets
 }