[Sync] Convert SyncSessionSnapshot to a copy-able class.

sync/engine/syncer_types.cc

Index: sync/engine/syncer_types.cc
diff --git a/sync/engine/syncer_types.cc b/sync/engine/syncer_types.cc
deleted file mode 100644
index 18994668559280bfb4460c3d125a34af43fcf290..0000000000000000000000000000000000000000
--- a/sync/engine/syncer_types.cc
+++ /dev/null
@@ -1,15 +0,0 @@
-// Copyright (c) 2012 The Chromium Authors. All rights reserved.
-// Use of this source code is governed by a BSD-style license that can be
-// found in the LICENSE file.
-
-#include "sync/engine/syncer_types.h"
-
-namespace browser_sync {
-
-SyncEngineEvent::SyncEngineEvent(EventCause cause) : what_happened(cause),
-                                                     snapshot(NULL) {
-}
-
-SyncEngineEvent::~SyncEngineEvent() {}
-
-}  // namespace browser_sync