GitLab

When we overscroll a scroller with non-auto overscroll-behavior at its
scroll extent, no node will be added to the scroll chain, because the
scroller can not consume the current delta. However, if we then scroll
the scroller to the opposite direction in the same gesture, the scroller
won't respond to that because it's not the CurrentlyScrollingNode.

This patch adds the first node with non-auto overscroll-behavior to the
scroll chain regardlessly, as it's the only node we can latch to, even
if it cannot consume the current delta. So when we change the scroll
direction, the scroller can still respond to the later events.

Bug: 798543
Cq-Include-Trybots: master.tryserver.blink:linux_trusty_blink_rel;master.tryserver.chromium.android:android_optional_gpu_tests_rel
Change-Id: I8baa77ae6690e095de3018cb112185f48f0854a8
Reviewed-on: https://chromium-review.googlesource.com/848314Reviewed-by: Ali Juma <ajuma@chromium.org>
Reviewed-by: David Bokan <bokan@chromium.org>
Commit-Queue: Sandra Sun <sunyunjia@chromium.org>
Cr-Commit-Position: refs/heads/master@{#527068}