move V2 classes in chrome/engine to syncer_v2 namespace

sync/internal_api/sync_context_proxy_impl.h

Index: sync/internal_api/sync_context_proxy_impl.h
diff --git a/sync/internal_api/sync_context_proxy_impl.h b/sync/internal_api/sync_context_proxy_impl.h
index 0a835efbc86079731538ab4531f938903893c7ae..979b3f3a29ee2ebd4c621fc0386f99358fe86cde 100644
--- a/sync/internal_api/sync_context_proxy_impl.h
+++ b/sync/internal_api/sync_context_proxy_impl.h
@@ -12,12 +12,8 @@
 #include "sync/internal_api/public/base/model_type.h"
 #include "sync/internal_api/public/sync_context_proxy.h"
 
-namespace syncer {
-class ModelTypeSyncProxyImpl;
-}
-
 namespace syncer_v2 {
-
+class ModelTypeSyncProxyImpl;
 class SyncContext;
 struct DataTypeState;
 
@@ -40,11 +36,11 @@ class SYNC_EXPORT_PRIVATE SyncContextProxyImpl : public SyncContextProxy {
   // unable to distinguish a slow success from failure.
   //
   // Must be called from the thread where the data type lives.
-  void ConnectTypeToSync(syncer::ModelType type,
-                         const DataTypeState& data_type_state,
-                         const UpdateResponseDataList& pending_updates,
-                         const base::WeakPtr<syncer::ModelTypeSyncProxyImpl>&
-                             sync_proxy_impl) override;
+  void ConnectTypeToSync(
+      syncer::ModelType type,
+      const DataTypeState& data_type_state,
+      const UpdateResponseDataList& pending_updates,
+      const base::WeakPtr<ModelTypeSyncProxyImpl>& sync_proxy_impl) override;
 
   // Disables syncing for the given type on the sync thread.
   void Disconnect(syncer::ModelType type) override;