[Android] Allow geolocation context permission for crosswalk.

Geolocation context permission has to be handled in crosswalk for Android
port. It's used to allow geolocation access for origins. This fix is to allow
requests from different origins for geolocation information with a
in-memory cache mechanism.
Currently we allow all origins to access the geolocation information
if the web app is granted with the permission.

BUG=https://crosswalk-project.org/jira/browse/XWALK-151