Wait until updateItems is called to perform addStaticViews.

This is more consistent with pre-LayoutTransition approach, and should
behave more reliably on phones.

Flag: com.android.window.flags.enable_taskbar_recents_layout_transition
Bug: 343521765
Test: go/testedequals
Change-Id: Ib758b1e44c3b87d6d2ff71425ed40ff621261104

quickstep/src/com/android/launcher3/taskbar/TaskbarView.java

@@ -129,7 +129,7 @@ public class TaskbarView extends FrameLayout implements FolderIcon.FolderIconPar
 
     private final int mAllAppsButtonTranslationOffset;
 
-    private final int mNumStaticViews;
+    private int mNumStaticViews;
 
     private Set<GroupTask> mPrevRecentTasks = Collections.emptySet();
     private Set<GroupTask> mPrevOverflowTasks = Collections.emptySet();
@@ -199,8 +199,6 @@ public class TaskbarView extends FrameLayout implements FolderIcon.FolderIconPar
 
         // TODO: Disable touch events on QSB otherwise it can crash.
         mQsb = LayoutInflater.from(context).inflate(R.layout.search_container_hotseat, this, false);
-
-        mNumStaticViews = ENABLE_TASKBAR_RECENTS_LAYOUT_TRANSITION.isTrue() ? addStaticViews() : 0;
     }
 
     /**
@@ -448,6 +446,10 @@ public class TaskbarView extends FrameLayout implements FolderIcon.FolderIconPar
     private void updateItemsWithLayoutTransition(
             ItemInfo[] hotseatItemInfos, List<GroupTask> recentTasks) {
 
+        if (mNumStaticViews == 0) {
+            mNumStaticViews = addStaticViews();
+        }
+
         // Skip static views and potential All Apps divider, if they are on the left.
         mNextViewIndex = mIsRtl ? 0 : mNumStaticViews;
         if (getChildAt(mNextViewIndex) == mTaskbarDividerContainer && !mAddedDividerForRecents) {