Update {virtual,override} to follow C++11 style in sync.

sync/internal_api/sync_manager_impl_unittest.cc

Index: sync/internal_api/sync_manager_impl_unittest.cc
diff --git a/sync/internal_api/sync_manager_impl_unittest.cc b/sync/internal_api/sync_manager_impl_unittest.cc
index daedba2ae73530aa5f0a4829471a07b48f5b71a9..80972bff39429fc31280d11597d44a03b81b0c5d 100644
--- a/sync/internal_api/sync_manager_impl_unittest.cc
+++ b/sync/internal_api/sync_manager_impl_unittest.cc
@@ -903,13 +903,13 @@ class SyncManagerTest : public testing::Test,
     return GetRoutingInfoTypes(routing_info);
   }
 
-  virtual void OnChangesApplied(
+  void OnChangesApplied(
       ModelType model_type,
       int64 model_version,
       const BaseTransaction* trans,
       const ImmutableChangeRecordList& changes) override {}
 
-  virtual void OnChangesComplete(ModelType model_type) override {}
+  void OnChangesComplete(ModelType model_type) override {}
 
   // Helper methods.
   bool SetUpEncryption(NigoriStatus nigori_status,