Extend background to full screen.

Gradient and black backgrounds were stopping at the Status Bar.
When returning from a full screen app to the launcher the wallpaper
was completely visible when it should have been obscured by these
backgrounds. Making the app full screen while keeping the views
within the system insets fixes this.

Bug 7410717 fixed.

Change-Id: If3f7e4808961ee6c80fe2d0a328e6ca39fa5eb7a
5 files changed