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diff --git a/security/sandbox/chromium/base/callback.h b/security/sandbox/chromium/base/callback.h
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+// Copyright (c) 2012 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.
+//
+// NOTE: Header files that do not require the full definition of
+// base::{Once,Repeating}Callback or base::{Once,Repeating}Closure should
+// #include "base/callback_forward.h" instead of this file.
+
+#ifndef BASE_CALLBACK_H_
+#define BASE_CALLBACK_H_
+
+#include <stddef.h>
+
+#include "base/callback_forward.h"
+#include "base/callback_internal.h"
+
+// -----------------------------------------------------------------------------
+// Usage documentation
+// -----------------------------------------------------------------------------
+//
+// Overview:
+// A callback is similar in concept to a function pointer: it wraps a runnable
+// object such as a function, method, lambda, or even another callback, allowing
+// the runnable object to be invoked later via the callback object.
+//
+// Unlike function pointers, callbacks are created with base::BindOnce() or
+// base::BindRepeating() and support partial function application.
+//
+// A base::OnceCallback may be Run() at most once; a base::RepeatingCallback may
+// be Run() any number of times. |is_null()| is guaranteed to return true for a
+// moved-from callback.
+//
+//   // The lambda takes two arguments, but the first argument |x| is bound at
+//   // callback creation.
+//   base::OnceCallback<int(int)> cb = base::BindOnce([] (int x, int y) {
+//     return x + y;
+//   }, 1);
+//   // Run() only needs the remaining unbound argument |y|.
+//   printf("1 + 2 = %d\n", std::move(cb).Run(2));  // Prints 3
+//   printf("cb is null? %s\n",
+//          cb.is_null() ? "true" : "false");  // Prints true
+//   std::move(cb).Run(2);  // Crashes since |cb| has already run.
+//
+// Callbacks also support cancellation. A common use is binding the receiver
+// object as a WeakPtr<T>. If that weak pointer is invalidated, calling Run()
+// will be a no-op. Note that |IsCancelled()| and |is_null()| are distinct:
+// simply cancelling a callback will not also make it null.
+//
+// base::Callback is currently a type alias for base::RepeatingCallback. In the
+// future, we expect to flip this to default to base::OnceCallback.
+//
+// See //docs/callback.md for the full documentation.
+
+namespace base {
+
+template <typename R, typename... Args>
+class OnceCallback<R(Args...)> : public internal::CallbackBase {
+ public:
+  using RunType = R(Args...);
+  using PolymorphicInvoke = R (*)(internal::BindStateBase*,
+                                  internal::PassingType<Args>...);
+
+  constexpr OnceCallback() = default;
+  OnceCallback(std::nullptr_t) = delete;
+
+  explicit OnceCallback(internal::BindStateBase* bind_state)
+      : internal::CallbackBase(bind_state) {}
+
+  OnceCallback(const OnceCallback&) = delete;
+  OnceCallback& operator=(const OnceCallback&) = delete;
+
+  OnceCallback(OnceCallback&&) noexcept = default;
+  OnceCallback& operator=(OnceCallback&&) noexcept = default;
+
+  OnceCallback(RepeatingCallback<RunType> other)
+      : internal::CallbackBase(std::move(other)) {}
+
+  OnceCallback& operator=(RepeatingCallback<RunType> other) {
+    static_cast<internal::CallbackBase&>(*this) = std::move(other);
+    return *this;
+  }
+
+  R Run(Args... args) const & {
+    static_assert(!sizeof(*this),
+                  "OnceCallback::Run() may only be invoked on a non-const "
+                  "rvalue, i.e. std::move(callback).Run().");
+    NOTREACHED();
+  }
+
+  R Run(Args... args) && {
+    // Move the callback instance into a local variable before the invocation,
+    // that ensures the internal state is cleared after the invocation.
+    // It's not safe to touch |this| after the invocation, since running the
+    // bound function may destroy |this|.
+    OnceCallback cb = std::move(*this);
+    PolymorphicInvoke f =
+        reinterpret_cast<PolymorphicInvoke>(cb.polymorphic_invoke());
+    return f(cb.bind_state_.get(), std::forward<Args>(args)...);
+  }
+};
+
+template <typename R, typename... Args>
+class RepeatingCallback<R(Args...)> : public internal::CallbackBaseCopyable {
+ public:
+  using RunType = R(Args...);
+  using PolymorphicInvoke = R (*)(internal::BindStateBase*,
+                                  internal::PassingType<Args>...);
+
+  constexpr RepeatingCallback() = default;
+  RepeatingCallback(std::nullptr_t) = delete;
+
+  explicit RepeatingCallback(internal::BindStateBase* bind_state)
+      : internal::CallbackBaseCopyable(bind_state) {}
+
+  // Copyable and movable.
+  RepeatingCallback(const RepeatingCallback&) = default;
+  RepeatingCallback& operator=(const RepeatingCallback&) = default;
+  RepeatingCallback(RepeatingCallback&&) noexcept = default;
+  RepeatingCallback& operator=(RepeatingCallback&&) noexcept = default;
+
+  bool operator==(const RepeatingCallback& other) const {
+    return EqualsInternal(other);
+  }
+
+  bool operator!=(const RepeatingCallback& other) const {
+    return !operator==(other);
+  }
+
+  R Run(Args... args) const & {
+    PolymorphicInvoke f =
+        reinterpret_cast<PolymorphicInvoke>(this->polymorphic_invoke());
+    return f(this->bind_state_.get(), std::forward<Args>(args)...);
+  }
+
+  R Run(Args... args) && {
+    // Move the callback instance into a local variable before the invocation,
+    // that ensures the internal state is cleared after the invocation.
+    // It's not safe to touch |this| after the invocation, since running the
+    // bound function may destroy |this|.
+    RepeatingCallback cb = std::move(*this);
+    PolymorphicInvoke f =
+        reinterpret_cast<PolymorphicInvoke>(cb.polymorphic_invoke());
+    return f(std::move(cb).bind_state_.get(), std::forward<Args>(args)...);
+  }
+};
+
+}  // namespace base
+
+#endif  // BASE_CALLBACK_H_