[ads] Fixes video NTT does not autoplay when opening a new tab
The PR fixes regression introduced in v1.90 when the video NTT
does not autoplay when opening a new tab. The fix ensures autoplay
fires on the first video NTT delivery in a tab and ignores subsequent
tab background changes.
The PR also fixed a race condition with New Tab Takeover infobar.
The race was introduced in v1.90, when NTTs started serving asyncronously.