Don't update nav bar tint when in gesture nav

- The region sampling listener is already constantly updating the tint
  based on the actual content beneath the bar

Change-Id: Ia521bd3c5c8507fd97e22dd12e8102dfc2368320
Bug: 154002408
Test: Open up the settings "opening links" activity and ensure it
      the tint doesn't get clobbered
4 files changed