Add a slaved events store class

Add a test to check that get_room_names_and_aliases does the same
thing on both the master and on the slave data store.

synapse/replication/slave/storage/_base.py

@@ -0,0 +1,28 @@
+# -*- coding: utf-8 -*-
+# Copyright 2016 OpenMarket Ltd
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+from synapse.storage._base import SQLBaseStore
+from twisted.internet import defer
+
+
+class BaseSlavedStore(SQLBaseStore):
+    def __init__(self, db_conn, hs):
+        super(BaseSlavedStore, self).__init__(hs)
+
+    def stream_positions(self):
+        return {}
+
+    def process_replication(self, result):
+        return defer.succeed(None)