Refactor DiscardableMemory for the upcoming DiscardableMemoryAllocator.

webkit/child/web_discardable_memory_impl.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 WEBKIT_CHILD_WEB_DISCARDABLE_MEMORY_IMPL_H_
 #define WEBKIT_CHILD_WEB_DISCARDABLE_MEMORY_IMPL_H_
 
+#include "base/basictypes.h"
 #include "base/memory/discardable_memory.h"
 #include "base/memory/scoped_ptr.h"
 #include "third_party/WebKit/public/platform/WebDiscardableMemory.h"
 #include "webkit/child/webkit_child_export.h"
 
 namespace WebKit {
 class WebDiscardableMemory;
 }
 
 namespace webkit_glue {
 
 // Implementation of WebDiscardableMemory that is responsible for allocating
 // discardable memory.
 class WEBKIT_CHILD_EXPORT WebDiscardableMemoryImpl
     : NON_EXPORTED_BASE(public WebKit::WebDiscardableMemory) {
  public:
-  WebDiscardableMemoryImpl();
   virtual ~WebDiscardableMemoryImpl();
 
-  // WebKit::WebDiscardableMemory implementation.
+  static scoped_ptr<WebDiscardableMemoryImpl> CreateLockedMemory(size_t size);
+
+  // WebKit::WebDiscardableMemory:
   virtual bool lock();
   virtual void unlock();
   virtual void* data();
 
-  // Initialize the WebDiscardableMemoryImpl 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 size);
+ private:
+  WebDiscardableMemoryImpl(scoped_ptr<base::DiscardableMemory> memory);
 
- private:
   scoped_ptr<base::DiscardableMemory> discardable_;
+
   DISALLOW_COPY_AND_ASSIGN(WebDiscardableMemoryImpl);
 };
 
 }  // namespace webkit_glue
 
 #endif  // WEBKIT_CHILD_WEB_DISCARDABLE_MEMORY_IMPL_H_