Refactor FakeAttachmentStore

sync/api/attachments/attachment_store.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 SYNC_API_ATTACHMENTS_ATTACHMENT_STORE_H_
 #define SYNC_API_ATTACHMENTS_ATTACHMENT_STORE_H_
 
 #include "base/callback.h"
 #include "base/memory/ref_counted.h"
 #include "base/memory/scoped_ptr.h"
 #include "sync/api/attachments/attachment.h"
 #include "sync/api/attachments/attachment_id.h"
 #include "sync/base/sync_export.h"
 
 namespace base {
 class RefCountedMemory;
 }  // namespace base
 
 namespace syncer {
 
 class Attachment;
 class AttachmentId;
 
 // A place to locally store and access Attachments.
 //
 // Destroying this object does not necessarily cancel outstanding async
 // operations. If you need cancel like semantics, use WeakPtr in the callbacks.
-class SYNC_EXPORT AttachmentStore : public base::RefCounted<AttachmentStore> {
+class SYNC_EXPORT AttachmentStoreBase {
  public:
-  AttachmentStore();
-
   // TODO(maniscalco): Consider udpating Read and Write methods to support
   // resumable transfers (bug 353292).
 
   enum Result {
     SUCCESS,            // No error, all completed successfully.
     UNSPECIFIED_ERROR,  // An unspecified error occurred for one or more items.
   };
 
   typedef base::Callback<void(const Result&,
                               scoped_ptr<AttachmentMap>,
                               scoped_ptr<AttachmentIdList>)> ReadCallback;
   typedef base::Callback<void(const Result&)> WriteCallback;
   typedef base::Callback<void(const Result&)> DropCallback;
 
+  AttachmentStoreBase();
+  virtual ~AttachmentStoreBase();
+
   // Asynchronously reads the attachments identified by |ids|.
   //
   // |callback| will be invoked when finished. AttachmentStore will attempt to
   // read all attachments specified in ids. If any of the attachments do not
   // exist or could not be read, |callback|'s Result will be UNSPECIFIED_ERROR.
   // Callback's AttachmentMap will contain all attachments that were
   // successfully read, AttachmentIdList will contain attachment ids of
   // attachments that are unavailable in attachment store, these need to be
   // downloaded from server.
   //
@@ skipping 18 matching lines @@
   //
   // This does not remove attachments from the server.
   //
   // |callback| will be invoked when finished. Attempting to drop an attachment
   // that does not exist is not an error. If any of the existing attachment
   // could not be dropped, |callback|'s Result will be UNSPECIFIED_ERROR. When
   // this happens, some or none of the attachments may have been dropped
   // successfully.
   virtual void Drop(const AttachmentIdList& ids,
                     const DropCallback& callback) = 0;
+};
+
+// AttachmentStore is an interface exposed to data type and AttachmentService
+// code. Also contains factory methods for default implementations.
+class SYNC_EXPORT AttachmentStore
+    : public AttachmentStoreBase,
+      public base::RefCountedThreadSafe<AttachmentStore> {
+ public:
+  AttachmentStore();
+
+  // Creates an AttachmentStoreHandle backed by in-memory implementation of
+  // attachment store. For now frontend lives on the same thread as backend.
+  static scoped_refptr<AttachmentStore> CreateInMemoryStore();
 
  protected:
-  friend class base::RefCounted<AttachmentStore>;
+  friend class base::RefCountedThreadSafe<AttachmentStore>;
   virtual ~AttachmentStore();
 };
 
 }  // namespace syncer
 
 #endif  // SYNC_API_ATTACHMENTS_ATTACHMENT_STORE_H_