rtc_use_h264 flag for building OpenH264/FFmpeg

webrtc/build/common.gypi

 # Copyright (c) 2012 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.
 
 # This file contains common settings for building WebRTC components.
 
@@ skipping 119 matching lines @@
     # enable schannel on windows.
     'use_legacy_ssl_defaults%': 0,
 
     # Determines whether NEON code will be built.
     'build_with_neon%': 0,
 
     # Enable this to use HW H.264 encoder/decoder on iOS/Mac PeerConnections.
     # Enabling this may break interop with Android clients that support H264.
     'use_objc_h264%': 0,
 
-    # Enable this to build H.264 encoder/decoder using third party libraries.
-    # Encoding uses OpenH264 and decoding uses FFmpeg. Because of this, OpenH264
-    # and FFmpeg have to be correctly enabled separately.
-    # - use_openh264=1 is required for OpenH264 targets to be defined.
-    # - ffmpeg_branding=Chrome is one way to support H.264 decoding in FFmpeg.
-    #   FFmpeg can be built with/without H.264 support, see 'ffmpeg_branding'.
-    #   Without it, it compiles but H264DecoderImpl fails to initialize.
+    # Enable this to build OpenH264 encoder/FFmpeg decoder. This is supported on
+    # all platforms except iOS. Because FFmpeg can be built with/without H.264
+    # support, |ffmpeg_branding| has to separately be set to a value that
+    # includes H.264, for example "Chrome". If FFmpeg is built without H.264,
+    # compilation succeeds but |H264DecoderImpl| fails to initialize.
     # CHECK THE OPENH264, FFMPEG AND H.264 LICENSES/PATENTS BEFORE BUILDING.
     # http://www.openh264.org, https://www.ffmpeg.org/
-    'use_third_party_h264%': 0,  # TODO(hbos): To be used in follow-up CL(s).
+#    'use_h264%': 0,  # TODO(hbos): enc/dec in follow up CL(s).

[kjellander_webrtc, 2016/01/20 19:28:45]

You don't need to define this here if you define it in both the if and the else
clause below.
Or is that why you've commented it? Either way this file needs to be updated.

[hbos, 2016/01/21 10:00:01]

(Since I couldn't remember supplement.gypi I did the if-else here, the commented
out line being how it should have been without the if-else)

 
     'conditions': [
+      ['OS!="ios"', {
+        'use_h264%': 1,
+      }, {
+        'use_h264%': 0,
+      }],
+
       ['build_with_chromium==1', {
         # Exclude pulse audio on Chromium since its prerequisites don't require
         # pulse audio.
         'include_pulse_audio%': 0,
 
         # Exclude internal ADM since Chromium uses its own IO handling.
         'include_internal_audio_device%': 0,
 
         # Remove tests for Chromium to avoid slowing down GYP generation.
         'include_tests%': 0,
@@ skipping 302 matching lines @@
           # of a more specific macro.
           'defines': [
             'WEBRTC_POSIX',
           ],
         }],
       ],
     },
   }, # target_defaults
 }