move V2 classes in chrome/engine to syncer_v2 namespace

sync/engine/model_type_sync_worker.h

Index: sync/engine/model_type_sync_worker.h
diff --git a/sync/engine/model_type_sync_worker.h b/sync/engine/model_type_sync_worker.h
index 182d5db83b5ed13484d2d5545e55f90d0ec7da39..081130c82a5c4b74eb67d822b59b937fdb72ab6a 100644
--- a/sync/engine/model_type_sync_worker.h
+++ b/sync/engine/model_type_sync_worker.h
@@ -7,7 +7,7 @@
 
 #include "sync/internal_api/public/non_blocking_sync_common.h"
 
-namespace syncer {
+namespace syncer_v2 {
 
 // Interface used by a synced data type to issue requests to the sync backend.
 class SYNC_EXPORT_PRIVATE ModelTypeSyncWorker {
@@ -16,8 +16,7 @@ class SYNC_EXPORT_PRIVATE ModelTypeSyncWorker {
   virtual ~ModelTypeSyncWorker();
 
   // Entry point for the ModelTypeSyncProxy to send commit requests.
-  virtual void EnqueueForCommit(
-      const syncer_v2::CommitRequestDataList& list) = 0;
+  virtual void EnqueueForCommit(const CommitRequestDataList& list) = 0;
 };
 
 }  // namespace syncer