GitLab

This CL adds the following network handling for the update required
screen :-
1) Metered(cellular) network at the start - Show dialog to connect to a
non metered network or accept update over metered. If good network is
connected, update starts. If accepted to update, update starts.
2) No network at the start - User is prompted to connect to a network.
When connected to a good network, update starts.
3) Good connection is lost and metered connected while updating -
User prompted to accept update over metered. If accepted, update
starts.

We register for the network updates only up to starting the update
process. Post that, the network changes are reflected in the update
engine result and thus, handled for there.

Bug: 1048607
Change-Id: I50d939c0152f76f4456830cdd5e07136819b91a5
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2091534
Commit-Queue: Saurabh Nijhara <snijhara@google.com>
Reviewed-by: Denis Kuznetsov [CET] <antrim@chromium.org>
Cr-Commit-Position: refs/heads/master@{#751463}