Fix bug where lockscreen notification is minimized and not dismissable

This happened because
- recently we started counting MediaHeaderView as part of
  maxDisplayedNotifications on lockscreen
- causing the last notification that should have shown on lockscreen
  to restrict itself to shelf height, and later be replaced
  with the shelf during layout; the shelf is not dismissable.

The fix is to
- ignore MediaHeaderView when counting shown notifications
- still include MediaHeaderView in contentHeight calculations

Fixes: 187304623
Test: have MediaHeaderView and many notifications on lockscreen
      and swipe away all of them individually
Change-Id: I4e122b9321856880a5a09e03df61698eaf6b5f54

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

@@ -2068,6 +2068,7 @@ public class NotificationStackScrollLayout extends ViewGroup implements Dumpable
         int height = 0;
         float previousPaddingRequest = mPaddingBetweenElements;
         int numShownItems = 0;
+        int numShownNotifs = 0;
         boolean finish = false;
         int maxDisplayedNotifications = mMaxDisplayedNotifications;
         ExpandableView previousView = null;
@@ -2077,7 +2078,7 @@ public class NotificationStackScrollLayout extends ViewGroup implements Dumpable
             if (expandableView.getVisibility() != View.GONE
                     && !expandableView.hasNoContentHeight() && !footerViewOnLockScreen) {
                 boolean limitReached = maxDisplayedNotifications != -1
-                        && numShownItems >= maxDisplayedNotifications;
+                        && numShownNotifs >= maxDisplayedNotifications;
                 final float viewHeight;
                 if (limitReached) {
                     viewHeight = mShelf.getIntrinsicHeight();
@@ -2090,7 +2091,11 @@ public class NotificationStackScrollLayout extends ViewGroup implements Dumpable
                 }
                 height += calculateGapHeight(previousView, expandableView, numShownItems);
                 height += viewHeight;
+
                 numShownItems++;
+                if (!(expandableView instanceof MediaHeaderView)) {
+                    numShownNotifs++;
+                }
                 previousView = expandableView;
                 if (finish) {
                     break;