Move base to DEPS

base/memory/discardable_memory.h

-// Copyright (c) 2013 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_MEMORY_DISCARDABLE_MEMORY_H_
-#define BASE_MEMORY_DISCARDABLE_MEMORY_H_
-
-#include "base/base_export.h"
-#include "base/basictypes.h"
-#include "base/compiler_specific.h"
-
-namespace base {
-
-// Discardable memory is used to cache large objects without worrying about
-// blowing out memory, both on mobile devices where there is no swap, and
-// desktop devices where unused free memory should be used to help the user
-// experience. This is preferable to releasing memory in response to an OOM
-// signal because it is simpler and provides system-wide management of
-// purgable memory, though it has less flexibility as to which objects get
-// discarded.
-//
-// Discardable memory has two states: locked and unlocked. While the memory is
-// locked, it will not be discarded. Unlocking the memory allows the
-// discardable memory system and the OS to reclaim it if needed. Locks do not
-// nest.
-//
-// Notes:
-//   - The paging behavior of memory while it is locked is not specified. While
-//     mobile platforms will not swap it out, it may qualify for swapping
-//     on desktop platforms. It is not expected that this will matter, as the
-//     preferred pattern of usage for DiscardableMemory is to lock down the
-//     memory, use it as quickly as possible, and then unlock it.
-//   - Because of memory alignment, the amount of memory allocated can be
-//     larger than the requested memory size. It is not very efficient for
-//     small allocations.
-//   - A discardable memory instance is not thread safe. It is the
-//     responsibility of users of discardable memory to ensure there are no
-//     races.
-//
-class BASE_EXPORT DiscardableMemory {
- public:
-  DiscardableMemory();
-  virtual ~DiscardableMemory();
-
-  // Locks the memory so that it will not be purged by the system. Returns
-  // true on success. If the return value is false then this object should be
-  // discarded and a new one should be created.
-  virtual bool Lock() WARN_UNUSED_RESULT = 0;
-
-  // Unlocks the memory so that it can be purged by the system. Must be called
-  // after every successful lock call.
-  virtual void Unlock() = 0;
-
-  // Returns the memory address held by this object. The object must be locked
-  // before calling this.
-  virtual void* data() const = 0;
-
-  // Handy method to simplify calling data() with a reinterpret_cast.
-  template<typename T> T* data_as() const {
-    return reinterpret_cast<T*>(data());
-  }
-};
-
-}  // namespace base
-
-#endif  // BASE_MEMORY_DISCARDABLE_MEMORY_H_