DialogFragement: Add null pointer check for mDialog for protection

DialogFragement can be dissmissed just after the Dialog is
established. This will cause NullPointerException.

Add null pointer check for mDialog for protection

CRs-fixed: 549689

Change-Id: If57f81d03a8ec2906598363b681ea38806fb2a90
SystemUI: Make percentage appear for hidden batt

This commit makes the battery percentage appear in QS when the user
chooses the "hidden battery" option as the battery style. Prior to
this commit, the same battery style was used for the QS tile just
without the percentage indicator. This means no major changes are
being introduced but the usability is being improved as the user
can glance at the QS tile to see the exact percentage instead of
being forced to open the linked Settings page.

Fixes AOSPA-687.

Change-Id: I2131332f2639721f99e149d3add0eb2877b4debe
Merge "DialogFragement: Add null pointer check for mDialog for protection" into kitkat
Merge remote-tracking branch 'aospa/kitkat' into kitkat