The Autofill server is now configured as a system setting. Add
that setting and a method to be called over JNI from the chrome
stack to retrieve it.
See also external/chromium change I3a22ae42402f52207eee2d0d9df64700cb7c9f45
Bug: 4515820
Change-Id: I0aa85c5bef834b1120baaabdc2dd2e4e607a63b6