[Sync] SyncEngine refactor part 1: interfaces.

components/sync/engine/sync_engine_host.cc

Index: components/sync/engine/sync_engine_host.cc
diff --git a/components/sync/driver/sync_frontend.cc b/components/sync/engine/sync_engine_host.cc
similarity index 62%
rename from components/sync/driver/sync_frontend.cc
rename to components/sync/engine/sync_engine_host.cc
index 9badf6a4ac87139e1b30072ff00744c0dbb433ea..7a19e8c1622e37852ba718b7be847355b55126c4 100644
--- a/components/sync/driver/sync_frontend.cc
+++ b/components/sync/engine/sync_engine_host.cc
@@ -2,12 +2,11 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-#include "components/sync/driver/sync_frontend.h"
+#include "components/sync/engine/sync_engine_host.h"
 
 namespace syncer {
 
-SyncFrontend::SyncFrontend() {}
-
-SyncFrontend::~SyncFrontend() {}
+SyncEngineHost::SyncEngineHost() {}
+SyncEngineHost::~SyncEngineHost() {}
 
 }  // namespace syncer