Standardize usage of virtual/override/final in sync/

sync/test/sessions/mock_debug_info_getter.h

Index: sync/test/sessions/mock_debug_info_getter.h
diff --git a/sync/test/sessions/mock_debug_info_getter.h b/sync/test/sessions/mock_debug_info_getter.h
index c0f8025059af4a34bca5b2a33f59c192a224903d..1ca833e57e246951f1fd7cce32f1dd5eaf93fd84 100644
--- a/sync/test/sessions/mock_debug_info_getter.h
+++ b/sync/test/sessions/mock_debug_info_getter.h
@@ -19,11 +19,11 @@ namespace sessions {
 class MockDebugInfoGetter : public sessions::DebugInfoGetter {
  public:
   MockDebugInfoGetter();
-  virtual ~MockDebugInfoGetter();
+  ~MockDebugInfoGetter() override;
 
   // DebugInfoGetter implementation.
-  virtual void GetDebugInfo(sync_pb::DebugInfo* debug_info) override;
-  virtual void ClearDebugInfo() override;
+  void GetDebugInfo(sync_pb::DebugInfo* debug_info) override;
+  void ClearDebugInfo() override;
 
   void AddDebugEvent();