Ability to disable the effects of |rtc_use_h264| with DisableRtcUseH264.

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': [
     '../../../../build/common.gypi',
   ],
   'targets': [
     {
       'target_name': 'webrtc_h264',
       'type': 'static_library',
       'conditions': [
         ['OS=="ios"', {
           'dependencies': [
             'webrtc_h264_video_toolbox',
           ],
           'sources': [
             'h264_objc.mm',
           ],
         }],
+        // TODO(hbos): Consider renaming this flag and the below macro to
+        // something which helps distinguish OpenH264/FFmpeg from other H264
+        // implementations.

[stefan-webrtc, 2016/02/03 07:51:14]

+1. Now the flag suggests that h264 is enabled/disabled entirely, when in fact
it's only the third_party implementations. HW may still work.

         ['rtc_use_h264==1', {
           'defines': [
-            'WEBRTC_THIRD_PARTY_H264',
+            'WEBRTC_USE_H264',
           ],
           'conditions': [
             ['rtc_initialize_ffmpeg==1', {
               'defines': [
                 'WEBRTC_INITIALIZE_FFMPEG',
               ],
             }],
           ],
           'dependencies': [
             '<(DEPTH)/third_party/ffmpeg/ffmpeg.gyp:ffmpeg',
@@ skipping 38 matching lines @@
             'h264_video_toolbox_encoder.cc',
             'h264_video_toolbox_encoder.h',
             'h264_video_toolbox_nalu.cc',
             'h264_video_toolbox_nalu.h',
           ],
         }, # webrtc_h264_video_toolbox
       ], # targets
     }], # OS=="ios"
   ], # conditions
 }