Fix animating between very different heights

 - Expand ViewHeightController so it can expand up or down
 - Control the height of all containers in the hierarchy
 - Intercept touch events and compensate for any top offset
   on the root view, since we expand upwards
 - Remove the current description from the description container
   so that it can shrink in relayout if necessary.

Bug: 21879037
Bug: 21784297
Change-Id: I3ad562158013b75c5e9150cbd91c96c6ff4941c9