Update {virtual,override,final} to follow C++11 style chrome/browser/ui/webui/chromeos.
The Google style guide states that only one of {virtual,override,final}
should be used for each declaration, since override implies virtual and
final implies both virtual and override.
This patch was automatically generated with a ChromeOS build using a
variation of https://codereview.chromium.org/598073004.
BUG=417463
R=dbeam@chromium.org
Review URL: https://codereview.chromium.org/854063002
Cr-Commit-Position: refs/heads/master@{#312302}
28 files changed
