Fix race condition in status bar init code.

There was a hole between the initial call to get the display
metrics and the attachment of the status bar to its window,
meaning there was an opportunity for the orientation to
change without the status bar's orientation change handler
being called. In this scenario the notification panel would
be sized for the wrong orientation until the configuration
changed again in some way.

Bug: 5509445
Change-Id: Ib1bff79c317945a61ccfccddc073cce015f34caa