Added utility base::BindLambda to allow passing lambdas as base::Callback<>

base/bind_lambda.h

+// Copyright (c) 2011 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 BASE_BIND_LAMBDA_H_
+#define BASE_BIND_LAMBDA_H_
+
+#include "base/bind.h"
+
+namespace base {
+namespace internal {
+
+template <typename T>
+struct RemoveObjectFromMemberFunction {};
+template <typename R, typename Z, typename... Args>
+struct RemoveObjectFromMemberFunction<R (Z::*)(Args...) const> {
+  typedef R(type)(Args...);
+};
+template <typename R, typename Z, typename... Args>
+struct RemoveObjectFromMemberFunction<R (Z::*)(Args...)> {
+  typedef R(type)(Args...);
+};
+
+template <typename LambdaType>
+struct LambdaTraits {
+  using LambdaSig = decltype(&LambdaType::operator());
+  using CallbackSig = typename RemoveObjectFromMemberFunction<LambdaSig>::type;
+  using CallbackType = Callback<CallbackSig>;
+};
+
+template <typename LambdaType>
+using LambdaCallback = typename LambdaTraits<LambdaType>::CallbackType;
+
+}  // namespace internal
+
+template <typename LambdaType>
+internal::LambdaCallback<LambdaType> BindLambda(const LambdaType& lambda) {
+  return Bind(&LambdaType::operator(), Owned(new LambdaType(lambda)));
+}
+
+}  // namespace base
+
+#endif  // BASE_BIND_LAMBDA_H_