weak_ptr_factory.cpp:35:38: warning: [chromium-style] WeakPtrFactory members which refer to their outer class must be the last member in the outer class definition.
  base::WeakPtrFactory<FactoryFirst> factory_;
                                     ^
weak_ptr_factory.cpp:41:39: warning: [chromium-style] WeakPtrFactory members which refer to their outer class must be the last member in the outer class definition.
  base::WeakPtrFactory<FactoryMiddle> factory_;
                                      ^
2 warnings generated.