No need to use getExpandedBubble for singleTaskDisplayDrawn/Empty callbacks

getExpandedBubble checks if the shade is expanded or not and returns
null if the shade is expanded, we don't care about that for the display
drawn callbacks.

Test: manual, have a bubble notification on lockscreen, tap it, note
      that the bubble is expanded & visible after going through lockscreen
Bug: 138461119
Change-Id: I00dff7cd3301db6a2613a947015ac0408b545202
diff --git a/packages/SystemUI/src/com/android/systemui/bubbles/BubbleController.java b/packages/SystemUI/src/com/android/systemui/bubbles/BubbleController.java
index 94d9ede..fb2f177 100644
--- a/packages/SystemUI/src/com/android/systemui/bubbles/BubbleController.java
+++ b/packages/SystemUI/src/com/android/systemui/bubbles/BubbleController.java
@@ -926,7 +926,9 @@
 
         @Override
         public void onSingleTaskDisplayDrawn(int displayId) {
-            final Bubble expandedBubble = getExpandedBubble(mContext);
+            final Bubble expandedBubble = mStackView != null
+                    ? mStackView.getExpandedBubble()
+                    : null;
             if (expandedBubble != null && expandedBubble.getDisplayId() == displayId) {
                 expandedBubble.setContentVisibility(true);
             }
@@ -934,7 +936,9 @@
 
         @Override
         public void onSingleTaskDisplayEmpty(int displayId) {
-            final Bubble expandedBubble = getExpandedBubble(mContext);
+            final Bubble expandedBubble = mStackView != null
+                    ? mStackView.getExpandedBubble()
+                    : null;
             if (expandedBubble == null) {
                 return;
             }