Wallpaper preview parallax matches the actual wallpaper's.

Cherry picking the following changes from ub-launcher3-master:
Change-Id: I41c5bbbfdabfeb4e20d77e9b5804842a03211edf
Change-Id: I69afa3f8cc59c77e9c4c25e29e8db8c4beb87462
Change-Id: I82b7ba506d51ee4b3812af5fbdf95d3303b37aef
Change-Id: Id7c2b5483c5535d59be2f8a459ce7788e3c8318a

Bug: 23568800
Change-Id: I343169b9fdc5ceaab3d4b39044627d78b7267868
(cherry picked from commit 3e776a87dc5178ab7d2c31a8db06fe5657db4e4a)