Deprecate EXTRA_PROXY_INFO and unhide ConnectivityManager.getDefaultProxy().

1. Unhide ConnectivityManager.getDefaultProxy() and update it to
   take into account process-bound-Networks.
2. Deprecate EXTRA_PROXY_INFO and instead encourage querying via
   getDefaultProxy().

Bug: 17905627
Bug: 17420465
Bug: 18144582

Change-Id: I45358ee82fe705d048022c8238b2452f52c37b88
4 files changed