Move crossThreadBind() from platform/ to wtf/

third_party/WebKit/Source/platform/CrossThreadFunctional.h

-// Copyright 2015 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 CrossThreadFunctional_h
-#define CrossThreadFunctional_h
-
-#include "base/bind.h"
-#include "wtf/CrossThreadCopier.h"
-#include "wtf/Functional.h"
-#include <type_traits>
-
-namespace blink {
-
-// crossThreadBind() is bind() for cross-thread task posting.
-// crossThreadBind() applies CrossThreadCopier to the arguments.
-//
-// Example:
-//     void func1(int, const String&);
-//     f = crossThreadBind(func1, 42, str);
-// func1(42, str2) will be called when |f()| is executed,
-// where |str2| is a deep copy of |str| (created by str.isolatedCopy()).
-//
-// crossThreadBind(str) is similar to bind(str.isolatedCopy()), but the latter
-// is NOT thread-safe due to temporary objects (https://crbug.com/390851).
-//
-// Don't (if you pass the task across threads):
-//     bind(func1, 42, str);
-//     bind(func1, 42, str.isolatedCopy());
-
-template<typename FunctionType, typename... Ps>
-std::unique_ptr<Function<base::MakeUnboundRunType<FunctionType, Ps...>, WTF::CrossThreadAffinity>> crossThreadBind(
-    FunctionType function,
-    Ps&&... parameters)
-{
-    return WTF::bindInternal<WTF::CrossThreadAffinity>(
-        function,
-        WTF::CrossThreadCopier<typename std::decay<Ps>::type>::copy(std::forward<Ps>(parameters))...);
-}
-
-} // namespace blink
-
-#endif // CrossThreadFunctional_h