Crash Fix When DeepLinkEnabled callback returns to a null Context.

DeepLinkEnabled request wasn't respecting lifecycle and could
execute after the context was no longer valid.  This cancels the
request in onPause() to better respect the lifecycle.

OPO-706

Change-Id: I3aa142ef8a749b9b5537b4af7b2c5438f3dcaa1f
(cherry picked from commit 560f3a89)