pdr@, looking at this closer, what do you expect is the problem with these tests? There's ~6-7 tests that are directly making assertions about viewport layers and their properties - these will have to be updated once we no longer create visual viewport layers. Are these tests what this bug refers to?

Otherwise, I expect the vast majority of the tests here wont need any changes. They load some html and then poke at the visual viewport and assert things about it. Unless I'm missing something, they shouldn't directly be building anything BGPT-related themselves. 

I don't know much about these tests, only that they need updating. If it's just 6-7 tests--that sounds great!

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/4940976efd556edfb4c1e1459d61c4a8be5ca842

commit 4940976efd556edfb4c1e1459d61c4a8be5ca842
Author: David Bokan <bokan@chromium.org>
Date: Wed Aug 22 14:44:58 2018

[blink-gen-property-trees] Update viewport tests

Update visual viewport unit tests for blink gen property trees. BGPT
still creates layers in the compositor so the changes are fairly
limited. In places where we check layer properties, this patch also adds
checks for the equivalent paint properties.

Bug:  836915 
Change-Id: I3d821cea1021b28d87ceff188931eaae3fa3b7c4
Reviewed-on: https://chromium-review.googlesource.com/1184963
Reviewed-by: Philip Rogers <pdr@chromium.org>
Commit-Queue: David Bokan <bokan@chromium.org>
Cr-Commit-Position: refs/heads/master@{#585014}
[modify] https://crrev.com/4940976efd556edfb4c1e1459d61c4a8be5ca842/third_party/blink/renderer/core/frame/visual_viewport_test.cc