Update include/base headers for C++11/14 (see issue #3140)

See the issue for update guidelines.

include/base/cef_callback_helpers.h

@@ -0,0 +1,241 @@
+// Copyright (c) 2014 Marshall A. Greenblatt. Portions copyright (c) 2012
+// Google Inc. All rights reserved.
+//
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions are
+// met:
+//
+//    * Redistributions of source code must retain the above copyright
+// notice, this list of conditions and the following disclaimer.
+//    * Redistributions in binary form must reproduce the above
+// copyright notice, this list of conditions and the following disclaimer
+// in the documentation and/or other materials provided with the
+// distribution.
+//    * Neither the name of Google Inc. nor the name Chromium Embedded
+// Framework nor the names of its contributors may be used to endorse
+// or promote products derived from this software without specific prior
+// written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+// This defines helpful methods for dealing with Callbacks.  Because Callbacks
+// are implemented using templates, with a class per callback signature, adding
+// methods to Callback<> itself is unattractive (lots of extra code gets
+// generated).  Instead, consider adding methods here.
+
+#ifndef CEF_INCLUDE_BASE_CEF_CALLBACK_HELPERS_H_
+#define CEF_INCLUDE_BASE_CEF_CALLBACK_HELPERS_H_
+#pragma once
+
+#if defined(USING_CHROMIUM_INCLUDES)
+// When building CEF include the Chromium header directly.
+#include "base/callback_helpers.h"
+#else  // !USING_CHROMIUM_INCLUDES
+// The following is substantially similar to the Chromium implementation.
+// If the Chromium implementation diverges the below implementation should be
+// updated to match.
+
+#include <atomic>
+#include <memory>
+#include <type_traits>
+#include <utility>
+
+#include "include/base/cef_bind.h"
+#include "include/base/cef_callback.h"
+#include "include/base/cef_compiler_specific.h"
+#include "include/base/cef_logging.h"
+
+namespace base {
+
+namespace internal {
+
+template <typename T>
+struct IsBaseCallbackImpl : std::false_type {};
+
+template <typename R, typename... Args>
+struct IsBaseCallbackImpl<OnceCallback<R(Args...)>> : std::true_type {};
+
+template <typename R, typename... Args>
+struct IsBaseCallbackImpl<RepeatingCallback<R(Args...)>> : std::true_type {};
+
+template <typename T>
+struct IsOnceCallbackImpl : std::false_type {};
+
+template <typename R, typename... Args>
+struct IsOnceCallbackImpl<OnceCallback<R(Args...)>> : std::true_type {};
+
+}  // namespace internal
+
+// IsBaseCallback<T>::value is true when T is any of the Closure or Callback
+// family of types.
+template <typename T>
+using IsBaseCallback = internal::IsBaseCallbackImpl<std::decay_t<T>>;
+
+// IsOnceCallback<T>::value is true when T is a OnceClosure or OnceCallback
+// type.
+template <typename T>
+using IsOnceCallback = internal::IsOnceCallbackImpl<std::decay_t<T>>;
+
+// SFINAE friendly enabler allowing to overload methods for both Repeating and
+// OnceCallbacks.
+//
+// Usage:
+// template <template <typename> class CallbackType,
+//           ... other template args ...,
+//           typename = EnableIfIsBaseCallback<CallbackType>>
+// void DoStuff(CallbackType<...> cb, ...);
+template <template <typename> class CallbackType>
+using EnableIfIsBaseCallback =
+    std::enable_if_t<IsBaseCallback<CallbackType<void()>>::value>;
+
+namespace internal {
+
+template <typename... Args>
+class OnceCallbackHolder final {
+ public:
+  OnceCallbackHolder(OnceCallback<void(Args...)> callback,
+                     bool ignore_extra_runs)
+      : callback_(std::move(callback)), ignore_extra_runs_(ignore_extra_runs) {
+    DCHECK(callback_);
+  }
+  OnceCallbackHolder(const OnceCallbackHolder&) = delete;
+  OnceCallbackHolder& operator=(const OnceCallbackHolder&) = delete;
+
+  void Run(Args... args) {
+    if (has_run_.exchange(true)) {
+      CHECK(ignore_extra_runs_) << "Both OnceCallbacks returned by "
+                                   "base::SplitOnceCallback() were run. "
+                                   "At most one of the pair should be run.";
+      return;
+    }
+    DCHECK(callback_);
+    std::move(callback_).Run(std::forward<Args>(args)...);
+  }
+
+ private:
+  volatile std::atomic_bool has_run_{false};
+  base::OnceCallback<void(Args...)> callback_;
+  const bool ignore_extra_runs_;
+};
+
+}  // namespace internal
+
+// Wraps the given OnceCallback into a RepeatingCallback that relays its
+// invocation to the original OnceCallback on the first invocation. The
+// following invocations are just ignored.
+//
+// Note that this deliberately subverts the Once/Repeating paradigm of Callbacks
+// but helps ease the migration from old-style Callbacks. Avoid if possible; use
+// if necessary for migration. TODO(tzik): Remove it. https://crbug.com/730593
+template <typename... Args>
+RepeatingCallback<void(Args...)> AdaptCallbackForRepeating(
+    OnceCallback<void(Args...)> callback) {
+  using Helper = internal::OnceCallbackHolder<Args...>;
+  return base::BindRepeating(
+      &Helper::Run, std::make_unique<Helper>(std::move(callback),
+                                             /*ignore_extra_runs=*/true));
+}
+
+// Wraps the given OnceCallback and returns two OnceCallbacks with an identical
+// signature. On first invokation of either returned callbacks, the original
+// callback is invoked. Invoking the remaining callback results in a crash.
+template <typename... Args>
+std::pair<OnceCallback<void(Args...)>, OnceCallback<void(Args...)>>
+SplitOnceCallback(OnceCallback<void(Args...)> callback) {
+  using Helper = internal::OnceCallbackHolder<Args...>;
+  auto wrapped_once = base::BindRepeating(
+      &Helper::Run, std::make_unique<Helper>(std::move(callback),
+                                             /*ignore_extra_runs=*/false));
+  return std::make_pair(wrapped_once, wrapped_once);
+}
+
+// ScopedClosureRunner is akin to std::unique_ptr<> for Closures. It ensures
+// that the Closure is executed no matter how the current scope exits.
+// If you are looking for "ScopedCallback", "CallbackRunner", or
+// "CallbackScoper" this is the class you want.
+class ScopedClosureRunner {
+ public:
+  ScopedClosureRunner();
+  explicit ScopedClosureRunner(OnceClosure closure);
+  ScopedClosureRunner(ScopedClosureRunner&& other);
+  // Runs the current closure if it's set, then replaces it with the closure
+  // from |other|. This is akin to how unique_ptr frees the contained pointer in
+  // its move assignment operator. If you need to explicitly avoid running any
+  // current closure, use ReplaceClosure().
+  ScopedClosureRunner& operator=(ScopedClosureRunner&& other);
+  ~ScopedClosureRunner();
+
+  explicit operator bool() const { return !!closure_; }
+
+  // Calls the current closure and resets it, so it wont be called again.
+  void RunAndReset();
+
+  // Replaces closure with the new one releasing the old one without calling it.
+  void ReplaceClosure(OnceClosure closure);
+
+  // Releases the Closure without calling.
+  OnceClosure Release() WARN_UNUSED_RESULT;
+
+ private:
+  OnceClosure closure_;
+};
+
+// Creates a null callback.
+class NullCallback {
+ public:
+  template <typename R, typename... Args>
+  operator RepeatingCallback<R(Args...)>() const {
+    return RepeatingCallback<R(Args...)>();
+  }
+  template <typename R, typename... Args>
+  operator OnceCallback<R(Args...)>() const {
+    return OnceCallback<R(Args...)>();
+  }
+};
+
+// Creates a callback that does nothing when called.
+class DoNothing {
+ public:
+  template <typename... Args>
+  operator RepeatingCallback<void(Args...)>() const {
+    return Repeatedly<Args...>();
+  }
+  template <typename... Args>
+  operator OnceCallback<void(Args...)>() const {
+    return Once<Args...>();
+  }
+  // Explicit way of specifying a specific callback type when the compiler can't
+  // deduce it.
+  template <typename... Args>
+  static RepeatingCallback<void(Args...)> Repeatedly() {
+    return BindRepeating([](Args... args) {});
+  }
+  template <typename... Args>
+  static OnceCallback<void(Args...)> Once() {
+    return BindOnce([](Args... args) {});
+  }
+};
+
+// Useful for creating a Closure that will delete a pointer when invoked. Only
+// use this when necessary. In most cases MessageLoop::DeleteSoon() is a better
+// fit.
+template <typename T>
+void DeletePointer(T* obj) {
+  delete obj;
+}
+
+}  // namespace base
+
+#endif  // !USING_CHROMIUM_INCLUDES
+
+#endif  // CEF_INCLUDE_BASE_CEF_CALLBACK_HELPERS_H_