Set always opaque flag on CarNavigationBar.

The navigation bar is more like a set of shortcuts on auto and
it doesn't make much sense for the application to be able to set
it to translucent.

Change-Id: Ibe0bcdd43b7b1c968a414bfe7de024a8422ee883

packages/SystemUI/src/com/android/systemui/statusbar/car/CarStatusBar.java

@@ -148,7 +148,7 @@ public class CarStatusBar extends PhoneStatusBar implements
         mController = new CarNavigationBarController(context, mCarNavigationBar,
                 this /* ActivityStarter*/);
         mNavigationBarView = mCarNavigationBar;
-
+        mCarNavigationBar.getBarTransitions().setAlwaysOpaque(true);
     }
 
     @Override