Keyboard Shortcut Viewer: first touch does not scroll the shortcut list

On ToT #582215 linux-chromeos builds (or similar on device)
(1) Run chrome --touch-devices=ID --ash-touch-hud (get ID from "xinput list")
(2) Open the KSV app window (Ctrl-Alt-/)
(3) Try to scroll the shortcut list with the very first touch
Expected: The first touch can scroll the view
Actual: The first touch causes the scrollbar to flash, but doesn't scroll

This also repros with the classic KSV app when disabling the KSV app feature flag.
The second touch scrolls fine, and the first touch will scroll if you previously scrolled with kbd/mouse.
Maybe this is related to ScrollView init (position, focus, etc.)?

I can't get a similar defect to repro with tall Views menus or the bookmark editor folder view.
For the bookmark editor folder view, the scrollbar flashes when the window first opens (not on first touch).
(perhaps something about the scroll view is being initialized late for the KSV?)

Tao, can you take a quick look? This is relatively low priority, but an odd issue.