GitLab

- -Wfinal-dtor-non-final-class warns on classes with final dtors but
  not final classes.
- Error messages are better when the class is marked final.
- Fix existing issues in code base and remove warning exemption

Bug: 999886
Test: no errors building
Change-Id: I85c8b03f3dab773e5fb017acdcf0b6682f1c9e01
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2466978
Commit-Queue: Zentaro Kavanagh <zentaro@chromium.org>
Reviewed-by: Nico Weber <thakis@chromium.org>
Cr-Commit-Position: refs/heads/master@{#816687}