Revert "Extend SwipeHelper to support vertical gestures"

This reverts commit 01ab5e0c9dd9067a9e6d9bf809a3d6c07d8ecfce.
Revert "Revert "Only show status bar blocker view if nav bar is translucent.""

This reverts commit 4890dd46078f98b5745978925f25cc0351fe92c1.