Add method to PowerManager that allows querying the lowest possible
brightness.

Used by the auto-brightness adjustment to adjust the sliders.

Change-Id: Idb58fd86dee1a053fe858291be6c9b3169ac4247
Make system layout fill the window properly on expanded desktop mode

This commit fixes e.g. the gap on the bottom of the lock screen
or the gap on the right side of status bar on landscape mode.

Patch set 2  : Remove whitespace issues
Patch set 3  : Code cleanup
Patch set 4  : Damn whitespace errors

Change-Id: Ic8a6b748f94d7dcc883201579d199898713c90fd
policy: always use hardware acceleration for keyguard

Without hardware acceleration, keyguard widget will appear aliased
and choppy (especially at the end of the scroll).

Change-Id: I1bfb6fbcba6306edf366e8ea752d6919936c3ab6