Eric, does this happen on a specific device, or it happens all over Android devices?

ericrk: sorry to reassign your own reported bug back to you, but if this is p1, then it needs an owner.  Can you find somebody to investigate?

Investigated this a bit:

Previous fixes address cases where a tile is potentially drawn (part of a layer that draws), but the layer's rects did not yet take into account top bar changes.

Unfortunately, they don't handle cases where we have earlier determined that an entire layer does not draw, and have marked the layer as not contributing to the drawn render surface:
https://cs.chromium.org/chromium/src/cc/layers/picture_layer_impl.cc?rcl=5c8c1f9cd0a4059a130e5b3797ab28d97ae8a6a2&l=1674

In these cases we won't even process tiles from the layer and our other fixes won't take effect.

It looks like we need to add a similar workaround somewhere earlier in our processing, maybe around here:
https://cs.chromium.org/chromium/src/cc/trees/layer_tree_host_common.cc?rcl=5c8c1f9cd0a4059a130e5b3797ab28d97ae8a6a2&l=362

Marking P2 as this is a long-standing bug (not a regression), but we should still fix this if someone has bandwidth.

 Issue 903689  has been merged into this issue.

Root cause of this issue and 903689 seems different.
903689 can be fixed if we revert the patch ttps://chromium-review.googlesource.com/c/chromium/src/+/723982
But this issue still happening. 

re #6,
The patch per #6 shouldn't be reverted because it removed an experimental feature.

The feature was skipping compositing small scrollers and with that we handled the  small scrollable areas on main thread and no compositor involved. After removing this feature via the patch per #6, the scrollable area gets composited again and the related logic is handled on the compositor where the bug is really from, as ericrk@ mentioned per #3.