[Android] Suppress pull-to-refresh when overscroll glow visible
Avoid accidental refreshes by suppressing the effect when the overscroll
glow animation is still visible. This naturally prevents the case where
the user repeatedly flings/scrolls to the top, releasing before they
realize that the scroll has turned into a pull-to-refresh.
Note that suppression is only provided on L; the glow effect on previous
platforms is both too long and too visually faint to provide a good feedback
signal for when the user can start pulling to refresh.
BUG=456300
Review URL: https://codereview.chromium.org/
879273007
Cr-Commit-Position: refs/heads/master@{#315832}