Refactor DiscardableMemory for the upcoming DiscardableMemoryAllocator.

skia/ext/SkDiscardableMemory_chrome.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 SKIA_EXT_SK_DISCARDABLE_MEMORY_CHROME_H_
 #define SKIA_EXT_SK_DISCARDABLE_MEMORY_CHROME_H_
 
 #include "base/memory/discardable_memory.h"
 #include "base/memory/scoped_ptr.h"
 #include "third_party/skia/src/core/SkDiscardableMemory.h"
 
 // This class implements the SkDiscardableMemory interface using
 // base::DiscardableMemory.
 class SK_API SkDiscardableMemoryChrome : public SkDiscardableMemory {
 public:
-  SkDiscardableMemoryChrome();
   virtual ~SkDiscardableMemoryChrome();
 
-  // Initialize the SkDiscardableMemoryChrome object and lock the memory.
-  // Returns true on success. No memory is allocated if this call returns
-  // false. This call should only be called once.
-  bool InitializeAndLock(size_t bytes);
-
-  // Implementation of SkDiscardableMemory interface.
+  // SkDiscardableMemory:
   virtual bool lock() OVERRIDE;
   virtual void* data() OVERRIDE;
   virtual void unlock() OVERRIDE;
 
 private:
+  friend class SkDiscardableMemory;
+
+  SkDiscardableMemoryChrome(scoped_ptr<base::DiscardableMemory> memory);
+
   scoped_ptr<base::DiscardableMemory> discardable_;
 };
 
 #endif  // SKIA_EXT_SK_DISCARDABLE_MEMORY_CHROME_H_