Update sync API to support attachments.

sync/api/attachments/attachment.h

Index: sync/api/attachments/attachment.h
diff --git a/sync/api/attachments/attachment.h b/sync/api/attachments/attachment.h
index 1f1dbd2a93463a74209d23bff4d89e68ff8d6931..3511e02cb7fee3ac536d595d9e8530dffe51f31b 100644
--- a/sync/api/attachments/attachment.h
+++ b/sync/api/attachments/attachment.h
@@ -27,17 +27,19 @@ class SYNC_EXPORT Attachment {
 
   // Default copy and assignment are welcome.
 
+  // Creates a unique attachment id.
+  static sync_pb::AttachmentId CreateId();
+
   // Creates an attachment with a unique id and the supplied data.
   //
   // Used when creating a brand new attachment.
-  static scoped_ptr<Attachment> Create(
-      const scoped_refptr<base::RefCountedMemory>& data);
+  static Attachment Create(const scoped_refptr<base::RefCountedMemory>& data);
 
   // Creates an attachment with the supplied id and data.
   //
   // Used when you want to recreate a specific attachment. E.g. creating a local
   // copy of an attachment that already exists on the sync server.
-  static scoped_ptr<Attachment> CreateWithId(
+  static Attachment CreateWithId(
       const sync_pb::AttachmentId& id,
       const scoped_refptr<base::RefCountedMemory>& data);
 
@@ -51,14 +53,8 @@ class SYNC_EXPORT Attachment {
   sync_pb::AttachmentId id_;
   scoped_refptr<base::RefCountedMemory> data_;
 
-  friend class AttachmentTest;
-  FRIEND_TEST_ALL_PREFIXES(AttachmentTest, CreateId_UniqueIdIsUnique);
-
   Attachment(const sync_pb::AttachmentId& id,
              const scoped_refptr<base::RefCountedMemory>& data);
-
-  // Creates a unique attachment id.
-  static sync_pb::AttachmentId CreateId();
 };
 
 typedef std::vector<syncer::Attachment> AttachmentList;