mSettingsObserver will be added only once to mContentQueryMap on first start,
but if you bring activity back to top, it will not be added any more.
Signed-off-by: Vladimir Baryshnikov <vovkab@gmail.com>
Didn't have an API for this before so people used a hacked system property (ro.carrier)
to determine if the device supported mobile data. Added new API and switching callsites.
bug:5087537
Change-Id: Ibd799559be102a9e2fd552d1a23d1afbcf8f4614
