Fix QS -> QQS animation.

- Show the "fancy" animation if the user has not scrolled down in QS
- Fix the "second page" animation to fade out the QS tiles as the QQS
tiles appear

Bug: 72736470
Test: visual
Change-Id: I30b7e004aafd8a96a0950499a91b88d887d6270e
diff --git a/packages/SystemUI/src/com/android/systemui/qs/QSPanel.java b/packages/SystemUI/src/com/android/systemui/qs/QSPanel.java
index 00b6c1e..bc02607 100644
--- a/packages/SystemUI/src/com/android/systemui/qs/QSPanel.java
+++ b/packages/SystemUI/src/com/android/systemui/qs/QSPanel.java
@@ -281,6 +281,20 @@
         }
     }
 
+    public void setPageListener(final PagedTileLayout.PageListener pageListener) {
+        if (mTileLayout instanceof PagedTileLayout) {
+            ((PagedTileLayout) mTileLayout).setPageListener(pageListener);
+        } else {
+            mScrollLayout.setOnScrollChangeListener(new OnScrollChangeListener() {
+                @Override
+                public void onScrollChange(View v, int scrollX, int scrollY, int oldScrollX,
+                        int oldScrollY) {
+                    pageListener.onPageChanged(scrollY == 0);
+                }
+            });
+        }
+    }
+
     public boolean isExpanded() {
         return mExpanded;
     }