[Sync] Remove SyncClient dep from SyncBackendRegistrar.

components/sync/driver/glue/sync_backend_host_impl.cc

Index: components/sync/driver/glue/sync_backend_host_impl.cc
diff --git a/components/sync/driver/glue/sync_backend_host_impl.cc b/components/sync/driver/glue/sync_backend_host_impl.cc
index 06d6c1ea71f9153aeffe00abb448733b702eac0d..cb23e3ce2f0cc59a0c26ff5a030452a620cd2bae 100644
--- a/components/sync/driver/glue/sync_backend_host_impl.cc
+++ b/components/sync/driver/glue/sync_backend_host_impl.cc
@@ -88,7 +88,9 @@ void SyncBackendHostImpl::Initialize(
   CHECK(sync_thread);
   sync_thread_ = sync_thread;
 
-  registrar_ = base::MakeUnique<SyncBackendRegistrar>(name_, sync_client_);
+  registrar_ = base::MakeUnique<SyncBackendRegistrar>(
+      name_, base::Bind(&SyncClient::CreateModelWorkerForGroup,
+                        base::Unretained(sync_client_)));
 
   DCHECK(frontend);
   frontend_ = frontend;