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 d487f8cd1775673a6cc3cee53b788e9f730f6c35..7a69b13b7f2a75a38e0d57f4c731bff41ea0e967 100644
--- a/sync/api/attachments/attachment_store.h
+++ b/sync/api/attachments/attachment_store.h
@@ -25,10 +25,8 @@ class AttachmentId;
 //
 // 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 {

[maniscalco, 2014/09/29 20:57:52]

Can/should ASB be made SYNC_PRIVATE?

[pavely, 2014/09/29 23:27:08]

It is base class for AttachmentStore which should be accessible from
tests/consumers, I don't think it should be SYNC_EXPORT_PRIVATE.
On 2014/09/29 20:57:52, maniscalco wrote:

[maniscalco, 2014/09/30 00:26:13]

You're right, I agree.

  public:
-  AttachmentStore();
-
   // TODO(maniscalco): Consider udpating Read and Write methods to support
   // resumable transfers (bug 353292).
 
@@ -43,6 +41,9 @@ class SYNC_EXPORT AttachmentStore : public base::RefCounted<AttachmentStore> {
   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
@@ -81,6 +82,18 @@ class SYNC_EXPORT AttachmentStore : public base::RefCounted<AttachmentStore> {
   // successfully.
   virtual void Drop(const AttachmentIdList& ids,
                     const DropCallback& callback) = 0;
+};
+
+// AttachmentStore is an interface exposed to device type and AttachmentService

[maniscalco, 2014/09/29 20:57:52]

s/device/data/

[pavely, 2014/09/29 23:27:07]

Done.

+// code. Also contains factory methods for default implementations.
+class SYNC_EXPORT AttachmentStore : public AttachmentStoreBase,
+                                    public base::RefCounted<AttachmentStore> {

[maniscalco, 2014/09/29 20:57:52]

I would be inclined to use RefCountedThreadSafe (here and elsewhere) instead of
just RC.  Here's my thinking.  Given how this type is used, the cost of mutexes
or atomic inc/dec in AddRef/Release is negligible.  I *think* RC might be good
enough for our uses, but there's a fair chance we may need to use RCTS in the
future and it would be easy to forget to upgrade from RC to RCTS.

[pavely, 2014/09/29 23:27:07]

Done.

+ public:
+  AttachmentStore();
+
+  // Creates an AttachmentStoreProxy 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>;