The summary for AllInOneTetherPreference in NetworkDashboardFragment is
updated according to tethering state and tether interface chosen by
user.
Bug: 149256198
Test: AllInOneTetherPreferenceControllerTest, TetherEnablerTest,
CodeInspectionTest
Change-Id: I24ba4deabbb02b203e76d32048040d7ccf1b2d22
Adding a MasterSwitchPreference into "Network & internet" and create
corresponding controller. The preference is hidden by the feature flag.
It does NOT affect the existing UI.
Bug: 146147778
Test: CodeInspectionTest, TetherPreferenceControllerTest,
NetworkDashboardFragmentTest
Change-Id: Ida8e088efbb22d0c983acecbc420672206392dad
