H.264 video codec support using OpenH264/FFmpeg

webrtc/modules/video_coding/BUILD.gn

 # Copyright (c) 2014 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.
 
 import("../../build/webrtc.gni")
 
@@ skipping 115 matching lines @@
 
   configs += [ "../..:common_config" ]
   public_configs = [ "../..:common_inherited_config" ]
 
   if (is_clang) {
     # Suppress warnings from Chrome's Clang plugins.
     # See http://code.google.com/p/webrtc/issues/detail?id=163 for details.
     configs -= [ "//build/config/clang:find_bad_constructs" ]
   }
 
+  defines = []
   deps = [
     "../../system_wrappers",
   ]
 
   if (use_third_party_h264) {
-    # Dependency added so that variables use_openh264 and ffmpeg_branding are
-    # recognized build arguments (avoid "Build argument has no effect" error).
-    # The variables and dependencies will be used for real as soon as
-    # https://codereview.webrtc.org/1306813009/ lands. In the meantime, the
-    # build arguments are to be used by waterfall/trybots.
+    defines += [ "WEBRTC_THIRD_PARTY_H264" ]
+    sources += [
+      "codecs/h264/h264_decoder_impl.cc",
+      "codecs/h264/h264_decoder_impl.h",
+      "codecs/h264/h264_encoder_impl.cc",
+      "codecs/h264/h264_encoder_impl.h",
+    ]
     deps += [
       "//third_party/ffmpeg:ffmpeg",
       "//third_party/openh264:encoder",
     ]
   }
 }
 
 # TODO(tkchin): Source set for webrtc_h264_video_toolbox. Currently not
 # possible to add, see https://crbug.com/297668.
 
@@ skipping 86 matching lines @@
 
   deps = [
     ":video_coding_utility",
     "../../common_video",
     "../../system_wrappers",
   ]
   if (rtc_build_libvpx) {
     deps += [ rtc_libvpx_dir ]
   }
 }