Currently, Tethering files NetworkRequests even when
config_tether_upstream_automatic is enabled. This is incorrect:
when the automatic upstream selection is enabled, the tethering
upstream should always follow the default network and there is
no need to file any requests.
These requests are harmful when tethering is not using cellular
as its upstream, because:
- If the device does not use mobile data always on, the request
causes the cellular network to be brought up, causing power
draw.
- Even if the device does use mobile data always on, the request
causes the cellular network to come to the foreground, which
allows all apps to access it, causing potential data usage.
Amend the existing testGetCurrentPreferredUpstream to cover these
changes, by making that test case always set automatic upstream
mode. This does not result in any loss of meaningful test
coverage, because getCurrentPreferredUpstream is only ever called
when chooseUpstreamAutomatically is enabled.
Bug: 173068192
Test: atest TetheringTests
Change-Id: I068a5338699a3ed04f24f97f785ea89ff5890e50
2bcde0fd97