GitLab

This change delegates the gesture events happening in the navigation
widget to the shelf

Fixed: 1016931
Change-Id: I4c91612ff5d4283a2f4b2d21a6c890dd33f34532
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1877140
Commit-Queue: Ana Salazar <anasalazar@chromium.org>
Reviewed-by: Manu Cornet <manucornet@chromium.org>
Cr-Commit-Position: refs/heads/master@{#709111}