Clear all notifications improvements

- Fix a bug with visibility.
- Improve fling behavior such that the shade open animation still
  looks like that we are decelerating towards the last card.

Change-Id: I1ad167ce0001ff6850f49e819bab944943fa529d
diff --git a/packages/SystemUI/src/com/android/systemui/statusbar/phone/NotificationPanelView.java b/packages/SystemUI/src/com/android/systemui/statusbar/phone/NotificationPanelView.java
index 909972a..b80a33b 100644
--- a/packages/SystemUI/src/com/android/systemui/statusbar/phone/NotificationPanelView.java
+++ b/packages/SystemUI/src/com/android/systemui/statusbar/phone/NotificationPanelView.java
@@ -1289,6 +1289,22 @@
     }
 
     @Override
+    protected boolean fullyExpandedClearAllVisible() {
+        return mNotificationStackScroller.isDismissViewNotGone()
+                && mNotificationStackScroller.isScrolledToBottom();
+    }
+
+    @Override
+    protected boolean isClearAllVisible() {
+        return mNotificationStackScroller.isDismissViewVisible();
+    }
+
+    @Override
+    protected int getClearAllHeight() {
+        return mNotificationStackScroller.getDismissViewHeight();
+    }
+
+    @Override
     protected boolean isTrackingBlocked() {
         return mConflictingQsExpansionGesture && mQsExpanded;
     }