Add testRegisterTetheringEventCallback for CtsTetheringTest

Bug: 150632712
Bug: 150631563
Test: atest CtsTetheringTest

Merged-In: I55895c8b26acb7ec905d75d1f4b2a8964b13187a
Change-Id: I55895c8b26acb7ec905d75d1f4b2a8964b13187a
1 file changed
tree: d82ba75e8fabf381b47ae4e465653d60eb43026d
  1. tests/