Move optional.h to webrtc/api/

webrtc/modules/rtp_rtcp/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("../../webrtc.gni")
 
@@ skipping 151 matching lines @@
   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 = [
     "..:module_api",
     "../..:webrtc_common",
     "../../api:array_view",
     "../../api:libjingle_peerconnection_api",
+    "../../api:optional",
     "../../api:transport_api",
     "../../api/audio_codecs:audio_codecs_api",
     "../../common_video",
     "../../logging:rtc_event_log_api",
     "../../rtc_base:gtest_prod",
     "../../rtc_base:rtc_base_approved",
     "../../rtc_base:sequenced_task_checker",
     "../../system_wrappers",
     "../audio_coding:audio_format_conversion",
     "../remote_bitrate_estimator",
@@ skipping 33 matching lines @@
 rtc_source_set("mock_rtp_rtcp") {
   testonly = true
   sources = [
     "mocks/mock_recovered_packet_receiver.h",
     "mocks/mock_rtcp_rtt_stats.h",
     "mocks/mock_rtp_rtcp.h",
   ]
   deps = [
     ":rtp_rtcp",
     "..:module_api",
+    "../../api:optional",
     "../../rtc_base:rtc_base_approved",
     "../../test:test_support",
   ]
 }
 
 if (rtc_include_tests) {
   rtc_executable("test_packet_masks_metrics") {
     testonly = true
 
     sources = [
@@ skipping 121 matching lines @@
     ]
 
     # TODO(jschuh): bugs.webrtc.org/1348: fix this warning.
     configs += [ "//build/config/compiler:no_size_t_to_int_warning" ]
     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" ]
     }
   }
 }