Delete Geolocation command line switch and callers of enableGeolocation.

The Geolocation API was launched a long time ago, and a mock is used in layout tests.
There are no unit tests so nothing needs to be set for them.

BUG=343592,36451

Review URL: https://codereview.chromium.org/164163002

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@251340 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 251340