GitLab

This CL adds handlers for "Learn More" and "Refresh" buttons on the
disconnected view.

Misc:
1. Minor refactoring on |PhoneHubTrayTest|.
2. Adds initial value for |num_schedule_connection_now_calls_|.

BUG=1106937,1126208
TEST=unittested.

Change-Id: I3e6c74b331710c1f6607865061f12267f8d27af6
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2439639
Commit-Queue: Meilin Wang <meilinw@chromium.org>
Reviewed-by: Kyle Horimoto <khorimoto@chromium.org>
Reviewed-by: Xiyuan Xia <xiyuan@chromium.org>
Reviewed-by: Tim Song <tengs@chromium.org>
Cr-Commit-Position: refs/heads/master@{#813311}