Make it clear that WeakPtrFactory is the last data member

Move declaration of AttachmentServiceProxyForTest's destructor to make
it clear the WeakPtrFactory is the last data member.

BUG=303818

Review URL: https://codereview.chromium.org/575383002

Cr-Commit-Position: refs/heads/master@{#295652}

sync/internal_api/public/attachments/attachment_service_proxy_for_test.h

@@ -32,12 +32,12 @@ class SYNC_EXPORT AttachmentServiceProxyForTest
         scoped_ptr<base::WeakPtrFactory<AttachmentService> > weak_ptr_factory);
 
    private:
+    virtual ~OwningCore();
+
     scoped_ptr<AttachmentService> wrapped_;
     // WeakPtrFactory for wrapped_.  See Create() for why this is a scoped_ptr.
     scoped_ptr<base::WeakPtrFactory<AttachmentService> > weak_ptr_factory_;
 
-    virtual ~OwningCore();
-
     DISALLOW_COPY_AND_ASSIGN(OwningCore);
   };