Reland "Trigger heavy ad intervention when an unloaded heavy ad navigates"

This is a reland of 312a57a1

Original change's description:
> Trigger heavy ad intervention when an unloaded heavy ad navigates
>
> Bug: 1099014
> Change-Id: I98a2d0e548a48fd93618fbae1c1d458f1dbd58a4
> Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2269740


> Reviewed-by: John Delaney <johnidel@chromium.org>
> Commit-Queue: Andrew Paseltiner <apaseltiner@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#791488}

Bug: 1099014
Change-Id: I0894d1f43127e3776e9f71bd35dcb723a1778ceb
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2356164


Reviewed-by: John Delaney <johnidel@chromium.org>
Commit-Queue: Andrew Paseltiner <apaseltiner@chromium.org>
Cr-Commit-Position: refs/heads/master@{#801381}