In isTetheringSupported, call isAdmin user from system.

This avoids requiring the MANAGE_USERS permission in this function.

Bug: 32671528
Test: Manual. Also seeking unit test guidance from reviewer.
Change-Id: I841e721013b0e4b6db34d629a1e97b3cd54cd73b
1 file changed
tree: d14284f48b77603d44cde3d9d768120f05422a0d
  1. core/
  2. services/
  3. tests/