Disable encoder scaling on iPhone4S.

webrtc/modules/video_coding/codecs/h264/h264.gypi

 # Copyright (c) 2015 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 61 matching lines @@
                 '-framework CoreFoundation',
                 '-framework CoreMedia',
                 '-framework CoreVideo',
                 '-framework VideoToolbox',
               ],
             },
           },
           'sources': [
             'h264_video_toolbox_decoder.cc',
             'h264_video_toolbox_decoder.h',
-            'h264_video_toolbox_encoder.cc',
             'h264_video_toolbox_encoder.h',
+            'h264_video_toolbox_encoder.mm',
             'h264_video_toolbox_nalu.cc',
             'h264_video_toolbox_nalu.h',
           ],
           'conditions': [
             ['build_libyuv==1', {
               'dependencies': ['<(DEPTH)/third_party/libyuv/libyuv.gyp:libyuv'],
             }],
           ],
         }, # webrtc_h264_video_toolbox
       ], # targets
     }], # OS=="ios"
   ], # conditions
 }