[Cast] Refactor ExternalVideoEncoder for cleaner/simpler encapsulation.

media/cast/cast_testing.gypi

 # 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.
 
 {
   'targets': [
     {
       # GN version: //media/cast:test_support
       'target_name': 'cast_test_utility',
       'type': 'static_library',
@@ skipping 98 matching lines @@
         'net/rtp/rtp_packetizer_unittest.cc',
         'net/rtp/rtp_receiver_defines.h',
         'net/udp_transport_unittest.cc',
         'receiver/audio_decoder_unittest.cc',
         'receiver/frame_receiver_unittest.cc',
         'receiver/video_decoder_unittest.cc',
         'sender/audio_encoder_unittest.cc',
         'sender/audio_sender_unittest.cc',
         'sender/congestion_control_unittest.cc',
         'sender/external_video_encoder_unittest.cc',
+        'sender/fake_video_encode_accelerator_factory.cc',
+        'sender/fake_video_encode_accelerator_factory.h',
         'sender/video_encoder_impl_unittest.cc',
         'sender/video_sender_unittest.cc',
         'test/end2end_unittest.cc',
         'test/fake_receiver_time_offset_estimator.cc',
         'test/fake_receiver_time_offset_estimator.h',
         'test/fake_single_thread_task_runner.cc',
         'test/fake_single_thread_task_runner.h',
         'test/utility/audio_utility_unittest.cc',
         'test/utility/barcode_unittest.cc',
       ], # source
@@ skipping 228 matching lines @@
             '<(DEPTH)/testing/gtest.gyp:gtest',
             '<(DEPTH)/third_party/ffmpeg/ffmpeg.gyp:ffmpeg',
           ],
           'sources': [
             'sender/h264_vt_encoder_unittest.cc',
           ],
       }], # targets
     }], # OS=="ios" or OS=="mac"
   ], # conditions
 }