H264: Thread-safe InitializeFFmpeg. Flag to control if InitializeFFmpeg should be called.

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 122 matching lines @@
     configs -= [ "//build/config/clang:find_bad_constructs" ]
   }
 
   defines = []
   deps = [
     "../../system_wrappers",
   ]
 
   if (rtc_use_h264) {
     defines += [ "WEBRTC_THIRD_PARTY_H264" ]
+    if (rtc_initialize_ffmpeg) {
+      defines += [ "WEBRTC_INITIALIZE_FFMPEG" ]
+    }
     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",
     ]
@@ skipping 90 matching lines @@
 
   deps = [
     ":video_coding_utility",
     "../../common_video",
     "../../system_wrappers",
   ]
   if (rtc_build_libvpx) {
     deps += [ rtc_libvpx_dir ]
   }
 }