Improve notification shade collapse code.

- Collapse after dismissing the last notification
- Avoid duplicate code paths for collapsing
- Improve variable naming according to AOSP review suggestions

Change-Id: Ic6f26a61f263c5beebbcc9725fe8914d3858576f
Make notification-shade-collapse-after-dismiss behaviour configurable.

Change-Id: I1be0be2753b479e6d2e4fc8e17d971d03ce01bb7
Re-add lockscreen music controls toggle.

Change-Id: I70fb6c0d20caad7af01a45b4a9374eb107a554a3
Fix Google Now animation.

Change-Id: I32efb2eb6dde3e1b45f4a7dd708003a85cfcc78b
Fix hidden navigation bar in expanded desktop mode not being correctly
reflected.

Change-Id: Ie40951c0787d3960a8e6e3b94544632f7633a376
Merge "Re-add lockscreen music controls toggle." into cm-10.2
Merge "Fix Google Now animation." into cm-10.2
Merge "Improve notification shade collapse code." into cm-10.2
Merge "Make notification-shade-collapse-after-dismiss behaviour configurable." into cm-10.2