- add private PackageManager APIs for setting/getting the default
Browser App package name
- serialize / deserialize the default Browser App package name per User
Also relax the Hosts name validation for the AppLinls feature. Now we
just care if the IntentFilter is having an HTTP or HTTPS scheme.
Change-Id: I4436f66ac6beff57e14f7f3a2a00b0b582c03be9