More dimming tweaks (for accessibility)

 - Don't dim when battery saver bar is showing.
 - Bump alpha by 10% for light nav bar

Test: manual
Change-Id: I296aa68c0904f7972dd941eb1aac3b4c71114eee
Fixes: 63630024
(cherry picked from commit cdec5ff9f496e345d1e2e40f3d36d66938ace5f6)
diff --git a/packages/SystemUI/src/com/android/systemui/statusbar/phone/NavigationBarTransitions.java b/packages/SystemUI/src/com/android/systemui/statusbar/phone/NavigationBarTransitions.java
index c950036..b81a3b0 100644
--- a/packages/SystemUI/src/com/android/systemui/statusbar/phone/NavigationBarTransitions.java
+++ b/packages/SystemUI/src/com/android/systemui/statusbar/phone/NavigationBarTransitions.java
@@ -80,7 +80,8 @@
 
     @Override
     protected boolean isLightsOut(int mode) {
-        return super.isLightsOut(mode) || (mAutoDim && !mWallpaperVisible);
+        return super.isLightsOut(mode) || (mAutoDim && !mWallpaperVisible
+                && mode != MODE_WARNING);
     }
 
     public LightBarTransitionsController getLightTransitionsController() {
@@ -108,7 +109,9 @@
         // ok, everyone, stop it right there
         navButtons.animate().cancel();
 
-        final float navButtonsAlpha = lightsOut ? 0.6f : 1f;
+        // Bump percentage by 10% if dark.
+        float darkBump = mLightTransitionsController.getCurrentDarkIntensity() / 10;
+        final float navButtonsAlpha = lightsOut ? 0.6f + darkBump : 1f;
 
         if (!animate) {
             navButtons.setAlpha(navButtonsAlpha);
@@ -130,6 +133,9 @@
         for (int i = buttonDispatchers.size() - 1; i >= 0; i--) {
             buttonDispatchers.valueAt(i).setDarkIntensity(darkIntensity);
         }
+        if (mAutoDim) {
+            applyLightsOut(false, true);
+        }
     }
 
     private final View.OnTouchListener mLightsOutListener = new View.OnTouchListener() {