Move optional.h to webrtc/api/

webrtc/media/BUILD.gn

 # Copyright (c) 2016 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/config/linux/pkg_config.gni")
 import("../webrtc.gni")
@@ skipping 27 matching lines @@
     "base/h264_profile_level_id.h",
   ]
 
   if (!build_with_chromium && is_clang) {
     # Suppress warnings from the Chromium Clang plugin (bugs.webrtc.org/163).
     suppressed_configs += [ "//build/config/clang:find_bad_constructs" ]
   }
 
   deps = [
     "..:webrtc_common",
+    "../api:optional",
     "../rtc_base:rtc_base",
     "../rtc_base:rtc_base_approved",
   ]
 }
 
 rtc_static_library("rtc_media_base") {
   # TODO(kjellander): Remove (bugs.webrtc.org/6828)
   # Enabling GN check triggers cyclic dependency error:
   #   :rtc_media_base ->
   #   ../pc:rtc_pc_base ->
@@ skipping 162 matching lines @@
   if (rtc_enable_protobuf) {
     deps += [ "../modules/audio_processing/aec_dump:aec_dump_impl" ]
   } else {
     deps += [ "../modules/audio_processing/aec_dump:null_aec_dump_factory" ]
   }
   deps += [
     ":rtc_media_base",
     "..:webrtc_common",
     "../api:call_api",
     "../api:libjingle_peerconnection_api",
+    "../api:optional",
     "../api:transport_api",
     "../api:video_frame_api",
     "../api/audio_codecs:audio_codecs_api",
     "../api/audio_codecs:builtin_audio_decoder_factory",
     "../api/audio_codecs:builtin_audio_encoder_factory",
     "../api/video_codecs:video_codecs_api",
     "../call",
     "../call:video_stream_api",
     "../common_video:common_video",
     "../modules/audio_coding:rent_a_codec",
@@ skipping 289 matching lines @@
       "../rtc_base:rtc_base_approved",
       "../rtc_base:rtc_base_tests_main",
       "../rtc_base:rtc_base_tests_utils",
       "../system_wrappers:metrics_default",
       "../test:audio_codec_mocks",
       "../test:test_support",
       "../voice_engine:voice_engine",
     ]
   }
 }