When the device is in portrait mode and the widget gets resized to be
narrow (2-by), the header background becomes corrupt. The new assets
now look correct at any size.
bug 3500861
Change-Id: I80a655c8822f2a14f9100afe32c893bf412ac936
* Add the background to the widget
* Updated background to a stretchable 9-patch
* Shift "Tap icon to change" text up a couple pixels
bug 3510984
Change-Id: I5ea65b802098c1af08e865f85fb5470e0a00b76b