Ensuring that we use the screen width more optimally in AllApps.

- Fixing issue with prediction bar height being calculated incorrectly
- Fixing issue where the prediction bar divider was not drawn exactly
  between the bar and the first row of apps
- Removing padding to allow scrollbars to reach full height

Bug: 20222023
Bug: 21335377
Change-Id: I2c0614a36e2294d0d6184a6bff4847876ffe971e