Notify expanding state for QS expand method

To alert the NotificationStackScroller of QS expansion so it can animate
appropriately

Test: manual
Fixes: 141655677
Change-Id: I78c8704d7fd2ed6bdc824d3021d2c91c1e049733

packages/SystemUI/src/com/android/systemui/statusbar/phone/NotificationPanelViewController.java

@@ -1779,8 +1779,14 @@ public class NotificationPanelViewController extends PanelViewController {
             setQsExpansion((Float) animation.getAnimatedValue());
         });
         animator.addListener(new AnimatorListenerAdapter() {
+            @Override
+            public void onAnimationStart(Animator animation) {
+                notifyExpandingStarted();
+            }
+
             @Override
             public void onAnimationEnd(Animator animation) {
+                notifyExpandingFinished();
                 mNotificationStackScroller.resetCheckSnoozeLeavebehind();
                 mQsExpansionAnimator = null;
                 if (onFinishRunnable != null) {

packages/SystemUI/src/com/android/systemui/statusbar/phone/PanelViewController.java

@@ -157,7 +157,7 @@ public abstract class PanelViewController {
     protected void onExpandingStarted() {
     }
 
-    private void notifyExpandingStarted() {
+    protected void notifyExpandingStarted() {
         if (!mExpanding) {
             mExpanding = true;
             onExpandingStarted();