Continue resource loading asynchronously to avoid issues during ResourceScheduler stack unwinding.

git-svn-id: http://chromiumembedded.googlecode.com/svn/trunk/cef3@1230 5089003a-bbd8-11dd-ad1f-f1f9622dbc98
Improve scheme handler documentation.

git-svn-id: http://chromiumembedded.googlecode.com/svn/trunk/cef3@1233 5089003a-bbd8-11dd-ad1f-f1f9622dbc98