Remove the flash specific disk cache backend.

net/disk_cache/flash/storage.h

-// 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.
-
-#ifndef NET_DISK_CACHE_FLASH_STORAGE_H_
-#define NET_DISK_CACHE_FLASH_STORAGE_H_
-
-#include "base/basictypes.h"
-#include "base/files/file.h"
-#include "net/base/net_export.h"
-
-namespace disk_cache {
-
-class NET_EXPORT_PRIVATE Storage {
- public:
-  Storage(const base::FilePath& path, int32 size);
-  bool Init();
-  ~Storage();
-
-  int32 size() const { return size_; }
-
-  bool Read(void* buffer, int32 size, int32 offset);
-  bool Write(const void* buffer, int32 size, int32 offset);
-
- private:
-  base::FilePath path_;
-  int32 size_;
-  base::File file_;
-
-  DISALLOW_COPY_AND_ASSIGN(Storage);
-};
-
-}  // namespace disk_cache
-
-#endif  // NET_DISK_CACHE_FLASH_STORAGE_H_