After unreverting the linkstate change patch, hook up notification handlers
that didn't exist when the first patch was created, like
EthernetDataTracker.java and Vpn.java.
For the observers that handle interfaceStatusChanged(), I made
interfaceLinkStatusChanged() call it so they both do the same thing.
Change-Id: I0077e5e5f48f3932ba98f5bf363243892f2de6cc
Signed-off-by: Mike J. Chen <mjchen@google.com>
f59c7d0f2a