[WebView] Interface to access hidden APIs. (DO NOT MERGE)

The WeView provider implementation needs access to
these APIs to implement the WebView functionality.

BUG:18152150

Change-Id: I6b41c623b1e8a776dcee8977d0d17259cb4b34f1
(cherry picked from commits 94ef789f0cf0387df20c2c602857ada1e5abfdd6
 and 53f256948724b8d4009d8a8a47da96a06402f9a2)