GitLab

- The back gesture contextual nudge ui will appear when a user navigates
to the second page within any Chrome apps in tablet mode.

Show frequency:
  * It only shows once per active day for over 3 days per user
  * and the user hasn't been done back gesture successfully for 7 times

Bug: 1009005b
Change-Id: Ide2dbf46be1dfcd0963d4466448f5a6ff5d62f9d
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2062917
Commit-Queue: Xiaoqian Dai <xdai@chromium.org>
Reviewed-by: Xiyuan Xia <xiyuan@chromium.org>
Cr-Commit-Position: refs/heads/master@{#742778}