Fix navigation bar icon color is not optimized for a dimming dialog

Bug: 193825236
Test: test passed on forrest
Change-Id: Ia898847d3eccc6408c6c77a56e0a935d694316fe

services/core/java/com/android/server/wm/DisplayPolicy.java

@@ -1917,7 +1917,7 @@ public class DisplayPolicy {
                 mStatusBarColorWindows.add(win);
                 mStatusBarColorCheckedBounds.union(sTmpRect);
             }
-            if (isOverlappingWithNavBar && mNavigationBar == null) {
+            if (isOverlappingWithNavBar && mNavBarColorWindowCandidate == null) {
                 mNavBarColorWindowCandidate = win;
             }
         }