[Sync] Adds a new switch for enabling the new local server backend.

components/sync/engine_impl/sync_manager_impl.h

Index: components/sync/engine_impl/sync_manager_impl.h
diff --git a/components/sync/engine_impl/sync_manager_impl.h b/components/sync/engine_impl/sync_manager_impl.h
index f7c761452cf34f41194496e90687478b1b46b73d..ed58d801b6f2670a68926034d0f9b9f05449daa4 100644
--- a/components/sync/engine_impl/sync_manager_impl.h
+++ b/components/sync/engine_impl/sync_manager_impl.h
@@ -38,7 +38,6 @@ class GURL;
 namespace syncer {
 
 class ModelTypeRegistry;
-class SyncServerConnectionManager;
 class SyncCycleContext;
 class TypeDebugInfoObserver;
 class WriteNode;
@@ -278,7 +277,7 @@ class SyncManagerImpl
 
   // The ServerConnectionManager used to abstract communication between the
   // client (the Syncer) and the sync server.
-  std::unique_ptr<SyncServerConnectionManager> connection_manager_;
+  std::unique_ptr<ServerConnectionManager> connection_manager_;
 
   // Maintains state that affects the way we interact with different sync types.
   // This state changes when entering or exiting a configuration cycle.