ServiceWorker: Introduce ServiceWorkerDiskCacheMigrator

content/browser/service_worker/service_worker_disk_cache.h

 // Copyright 2014 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 CONTENT_BROWSER_SERVICE_WORKER_SERVICE_WORKER_DISK_CACHE_H_
 #define CONTENT_BROWSER_SERVICE_WORKER_SERVICE_WORKER_DISK_CACHE_H_
 
 #include "content/browser/appcache/appcache_disk_cache.h"
 #include "content/common/content_export.h"
 
 namespace content {
 
 // Wholesale reusage of the appcache code for response reading,
 // writing, and storage. See the corresponding class in that
 // library for doc comments and other details.
 // TODO(michaeln): If this reuse sticks, refactor/move the
 // resused classes to a more common location.
 
 class CONTENT_EXPORT ServiceWorkerDiskCache
     : public AppCacheDiskCache {
+ public:
+  static scoped_ptr<ServiceWorkerDiskCache> CreateWithBlockFileBackend();
+  static scoped_ptr<ServiceWorkerDiskCache> CreateWithSimpleBackend();
+
+ private:
+  friend class ServiceWorkerDiskCacheMigrator;
+  friend class ServiceWorkerDiskCacheMigratorTest;
+  explicit ServiceWorkerDiskCache(bool use_simple_cache);
 };
 
 class CONTENT_EXPORT ServiceWorkerResponseReader
     : public AppCacheResponseReader {
  protected:
   // Should only be constructed by the storage class.
+  friend class ServiceWorkerDiskCacheMigrator;
+  friend class ServiceWorkerDiskCacheMigratorTest;
   friend class ServiceWorkerStorage;
   ServiceWorkerResponseReader(
       int64 response_id,
       ServiceWorkerDiskCache* disk_cache);
 };
 
 class CONTENT_EXPORT ServiceWorkerResponseWriter
     : public AppCacheResponseWriter {
  protected:
   // Should only be constructed by the storage class.
+  friend class ServiceWorkerDiskCacheMigrator;
+  friend class ServiceWorkerDiskCacheMigratorTest;
   friend class ServiceWorkerStorage;
   ServiceWorkerResponseWriter(
       int64 response_id,
       ServiceWorkerDiskCache* disk_cache);
 };
 
 class CONTENT_EXPORT ServiceWorkerResponseMetadataWriter
     : public AppCacheResponseMetadataWriter {
  protected:
   // Should only be constructed by the storage class.
+  friend class ServiceWorkerDiskCacheMigrator;
+  friend class ServiceWorkerDiskCacheMigratorTest;
   friend class ServiceWorkerStorage;
   ServiceWorkerResponseMetadataWriter(int64 response_id,
                                       ServiceWorkerDiskCache* disk_cache);
 };
 
 }  // namespace content
 
 #endif  // CONTENT_BROWSER_SERVICE_WORKER_SERVICE_WORKER_DISK_CACHE_H_