------ At the appointment on 20th March, my extension failed to return anything on Rafa's Mac laptop.
I used several Gmail accounts to check if my chrome extension is still working. After a few tests, now I know that Google have again changed the implementation of Gmail backend. The reason why the impact to my extension is huge is that my extension bases fully on the underlying internet protocol, rather than Gmail api provided by Google development team.
??? My solution is that I will re-implement the extension with offical Gmail api with goog documentation.