Move optional.h to webrtc/api/

webrtc/api/optional.cc

 /*
  *  Copyright 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.
  */
 
-#include "webrtc/rtc_base/optional.h"
+#include "webrtc/api/optional.h"
 
 namespace rtc {
 namespace optional_internal {
 
 #if RTC_HAS_ASAN
 
-void* FunctionThatDoesNothingImpl(void* x) { return x; }
+void* FunctionThatDoesNothingImpl(void* x) {
+  return x;
+}
 
 #endif
 
 }  // namespace optional_internal
 }  // namespace rtc