DO NOT MERGE Add logging to detect the start of a sync problem.

This should be removed prior to shipment!

The DctController is getting out of sync with the ApnContexts.  Add a callback
mechanism so the ApnContexts can let DctController know when they apply a change
and then when all is quiet we can compare and verify everything is good.

Potentially can fix the problem detected too (if there should be no live requests, nuke
the ref counts) but currently turned off so people will notice problems (battery life) and
file bugreports with the data of how it started.

bug:22632129
Change-Id: I84a67687f0b6dc43b2e429943935f4045ffc51ed