headless: Implement client API generation

headless/public/util/maybe.h

 // Copyright 2016 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef HEADLESS_PUBLIC_UTIL_MAYBE_H_
 #define HEADLESS_PUBLIC_UTIL_MAYBE_H_
 
 #include <algorithm>
 
 #include "base/logging.h"
 #include "base/macros.h"
 
 namespace headless {
 
 // A simple Maybe which may or may not have a value. Based on v8::Maybe.
+// TODO(skyostil): Replace this with base::Optional once it is available.
 template <typename T>
 class Maybe {
  public:
   Maybe() : has_value_(false) {}
 
   bool IsNothing() const { return !has_value_; }
   bool IsJust() const { return has_value_; }
 
   // Will crash if the Maybe<> is nothing.
   T& FromJust() {
@@ skipping 57 matching lines @@
 }
 
 template <class T>
 Maybe<typename std::remove_reference<T>::type> Just(T&& t) {
   return Maybe<typename std::remove_reference<T>::type>(std::move(t));
 }
 
 }  // namespace headless
 
 #endif  // HEADLESS_PUBLIC_UTIL_MAYBE_H_