Rationale: many users are confused about what to do after tapping the captive
portal network in Settings, and since there is explicit user action to
connect to that network at that point, auto-opening the portal is
natural and makes it simpler.
Bug: 148538768
Test: manually with local AP with Captive Portal and:
> make RunSettingsRoboTests -j40
> atest com.android.server.ConnectivityServiceTest
Change-Id: I29573132cd3e46ff22e6f67bb3678516fabac47d
Switch from polling for the first connected WiFi network to observing
the currently connected WiFi network and associating that with the
preference at the time the preference is created or updated.
Whenever the ConnectedAccessPointPreference is removed or UI is stopped
unregister the callback.
Bug:68031656
Test: make RunSettingsRoboTests
Change-Id: I5d1ed83b6a13e8a83fae04bfdce8d0f13c2ba0ac
