Make power control widget be more responsive. Fix StrictMode violations.

Also use new location providers changed broadcast intent, and fix a bug
introduced in Froyo where we stopped observing the SYSTEM_CLOSE_DIALOGS
intent so we fell out of sync (more often) with the sync settings.

Now even responsive during the boot I/O storm!  (except for toggling
brightness, which still does disk writes from the UI thread...)

BUG=2956025

Change-Id: I77876ff6e0be2325c15d5f08bb2970edf233f839