GitLab

This moves all of the responsibility for handling PageAlmostIdle to TabLoadTracker.

Change-Id: I9325109e896910d76b6aa6a615f9004dc1a4e67d
Reviewed-on: https://chromium-review.googlesource.com/1060569
Commit-Queue: Chris Hamilton <chrisha@chromium.org>
Reviewed-by: Sébastien Marchand <sebmarchand@chromium.org>
Reviewed-by: François Doray <fdoray@chromium.org>
Cr-Commit-Position: refs/heads/master@{#559277}