Update {virtual,override} to follow C++11 style in content/renderer/media.
This CL has just two files which got some extra "while I'm in there" cleanup while doing mechanical fixups across the codebase.
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.
BUG=417463
Review URL: https://codereview.chromium.org/1106043002
Cr-Commit-Position: refs/heads/master@{#326972}
2 files changed
