base: Refactor DiscardableMemoryProvider to build and be tested on all platforms.

base/memory/discardable_memory_emulated.h

+// Copyright 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_EMULATED_H_
+#define BASE_MEMORY_DISCARDABLE_MEMORY_EMULATED_H_
+
+#include "base/memory/discardable_memory.h"
+
+namespace base {
+namespace internal {
+
+class DiscardableMemoryEmulated : public DiscardableMemory {
+ public:
+  explicit DiscardableMemoryEmulated(size_t size);
+  virtual ~DiscardableMemoryEmulated();
+
+  static void PurgeForTesting();
+
+  bool Initialize();
+
+  // Overridden from DiscardableMemory:
+  virtual LockDiscardableMemoryStatus Lock() OVERRIDE;
+  virtual void Unlock() OVERRIDE;
+  virtual void* Memory() const OVERRIDE;
+
+ private:
+  scoped_ptr<uint8, FreeDeleter> memory_;
+  bool is_locked_;
+
+  DISALLOW_COPY_AND_ASSIGN(DiscardableMemoryEmulated);
+};
+
+}  // namespace internal
+}  // namespace base
+
+#endif  // BASE_MEMORY_DISCARDABLE_MEMORY_EMULATED_H_