Refinement of auto-dimming nav

 - Make dimming only happen for interaction with nav
 - Extend time to dim
 - Shorten time to start dimming by same amount.

Test: visual
Change-Id: Ieb5b31bacdde9ce1952601ad65cff2d54386dd0f
Fixes: 65694001
(cherry picked from commit 276f78eeaa77e8b9d6a3800182155c9eda10ee0d)
2 files changed