Check bubble count for initial state animation

With optional overflow, we need to check for actual bubble count
before animating the bubble bar to its initial state.

Flag: com.android.wm.shell.enable_bubble_bar
Fixes: 359403793
Test: manual
       - create first bubble on home
       - observe bubble bar animates correctly to initial state
       - add second bubble
       - observe bubble bar bounces correctly and does not slide
         in from the bottom of the screen
Change-Id: I53a34bc00b24e8a6504bcca0532054755554b9ac

quickstep/src/com/android/launcher3/taskbar/bubbles/BubbleBarViewController.java

@@ -579,9 +579,8 @@ public class BubbleBarViewController {
     public void animateBubbleNotification(BubbleBarBubble bubble, boolean isExpanding,
             boolean isUpdate) {
         boolean isInApp = mTaskbarStashController.isInApp();
-        // if this is the first bubble, animate to the initial state. one bubble is the overflow
-        // so check for at most 2 children.
-        if (mBarView.getChildCount() <= 2 && !isUpdate) {
+        // if this is the first bubble, animate to the initial state.
+        if (mBarView.getBubbleChildCount() == 1 && !isUpdate) {
             mBubbleBarViewAnimator.animateToInitialState(bubble, isInApp, isExpanding);
             return;
         }