Working around overscroll issues in AllApps.

- For the time being, we are going to do custom drawing to ensure that we get the touch
  events in the right order, while still allowing the recycler view to draw the overscroll
  effect on top of the prediction bar.

Bug: 21335369
Change-Id: I6bf64e5c1e9aa634a953223a5decf74942e4fb57