Revert of Refactor FakeAttachmentStore

sync/api/attachments/attachment_store.h

Index: sync/api/attachments/attachment_store.h
diff --git a/sync/api/attachments/attachment_store.h b/sync/api/attachments/attachment_store.h
index 45ccaf9c8efa355eaa53862eaf89463fc86c97eb..d487f8cd1775673a6cc3cee53b788e9f730f6c35 100644
--- a/sync/api/attachments/attachment_store.h
+++ b/sync/api/attachments/attachment_store.h
@@ -25,8 +25,10 @@
 //
 // Destroying this object does not necessarily cancel outstanding async
 // operations. If you need cancel like semantics, use WeakPtr in the callbacks.
-class SYNC_EXPORT AttachmentStoreBase {
+class SYNC_EXPORT AttachmentStore : public base::RefCounted<AttachmentStore> {
  public:
+  AttachmentStore();
+
   // TODO(maniscalco): Consider udpating Read and Write methods to support
   // resumable transfers (bug 353292).
 
@@ -40,9 +42,6 @@
                               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|.
   //
@@ -82,22 +81,9 @@
   // 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::RefCountedThreadSafe<AttachmentStore>;
+  friend class base::RefCounted<AttachmentStore>;
   virtual ~AttachmentStore();
 };