GitLab

Changes,
1. Don't handle the scroll gesture events in AppListButton::OnGestureEvent, let
   the ShelfView handle it instead.
2. Add a test for the swiping on applist button to open launcher.

Bug: 758071
Change-Id: I71557411e9de6cd21bdb76c52dfb545a1e621783
Reviewed-on: https://chromium-review.googlesource.com/685535
Commit-Queue: min c <minch@chromium.org>
Reviewed-by: Xiyuan Xia <xiyuan@chromium.org>
Cr-Commit-Position: refs/heads/master@{#504492}