Fix bug where shade is infinitely squishy after wallpaper change

This change fixes a bug where
opening an empty shade after wallpaper update
=> messes up qs button unfurling
=> hides the "no notifications" text

This bug happened because
=> wallpaper change causes theme change
=> on theme change, NSSLC reinflates EmptyShadeView
   with visibility=false
=> nothing resets EmptyShadeView visiblity=true on shade open
=> AmbientState has 0 visibleChildren during shade open,
   so stackHeight is 0 and expansionFraction is infinity

The solution is to have NSSLC
update EmptyShadeView visibility after re-inflation.

Fixes: 215038354
Fixes: 218501868
Fixes: 218380326
Test: have no notifications, change wallpaper, open shade
     => qs button squishiness animates fine
     => "no notifications" text shows up fine
     => log squishiness: no infinity or NaN

Change-Id: Iaa10605079db7edc79771a1cd9f4cc17f847c4cb

packages/SystemUI/src/com/android/systemui/statusbar/notification/stack/NotificationStackScrollLayoutController.java

@@ -288,11 +288,11 @@ public class NotificationStackScrollLayoutController {
 
         @Override
         public void onThemeChanged() {
-            updateShowEmptyShadeView();
             mView.updateCornerRadius();
             mView.updateBgColor();
             mView.updateDecorViews();
             mView.reinflateViews();
+            updateShowEmptyShadeView();
             updateFooter();
         }
 

packages/SystemUI/src/com/android/systemui/statusbar/notification/stack/StackScrollAlgorithm.java

@@ -376,6 +376,11 @@ public class StackScrollAlgorithm {
 
         final float stackHeight = ambientState.getStackHeight()  - shelfHeight - scrimPadding;
         final float stackEndHeight = ambientState.getStackEndHeight() - shelfHeight - scrimPadding;
+        if (stackEndHeight == 0f) {
+            // This should not happen, since even when the shade is empty we show EmptyShadeView
+            // but check just in case, so we don't return infinity or NaN.
+            return 0f;
+        }
         return stackHeight / stackEndHeight;
     }