[Sync] Add bookmark move tests.

sync/test/fake_server/fake_server.h

Index: sync/test/fake_server/fake_server.h
diff --git a/sync/test/fake_server/fake_server.h b/sync/test/fake_server/fake_server.h
index 1ae8e118046b261a8e1d8aaf178c5b9132ccd2d3..a940fddab024f74d1fb9b9da79d934059c3d8d27 100644
--- a/sync/test/fake_server/fake_server.h
+++ b/sync/test/fake_server/fake_server.h
@@ -82,6 +82,10 @@ class FakeServer {
   bool ModifyEntitySpecifics(const std::string& id,
                              const sync_pb::EntitySpecifics& updated_specifics);
 
+  bool ModifyBookmarkEntity(const std::string& id,
+                            const std::string& parent_id,
+                            const sync_pb::EntitySpecifics& updated_specifics);
+
   // Clears server data simulating a "dashboard stop and clear" and sets a new
   // store birthday.
   void ClearServerData();