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- Change the states in enable hotspot to fit new design.
- Add a notification when enable hotspot fails.

BUG=1106937,1126208

Change-Id: Id9092649d5cfcee9f6153c74a258b869a81f89dd
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2495621
Commit-Queue: Andre Le <leandre@chromium.org>
Reviewed-by: Xiyuan Xia <xiyuan@chromium.org>
Reviewed-by: Tim Song <tengs@chromium.org>
Reviewed-by: Kyle Horimoto <khorimoto@chromium.org>
Cr-Commit-Position: refs/heads/master@{#821374}