GitLab

Refactor the handling functions for gesture scrolling in
ScrollableShelfView. This CL makes preparations for the incoming
CL which handles the gesture fling event.

Bug: 973481
Change-Id: Ia25daf84043e38c0c03f7dbf73b7beb204b5bcab
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1760545
Commit-Queue: Andrew Xu <andrewxu@chromium.org>
Reviewed-by: Xiyuan Xia <xiyuan@chromium.org>
Cr-Commit-Position: refs/heads/master@{#688269}