TAPL waits for widgets recycler to become scrollable

On the Launcher side, moving setLayoutFrozen from the posted action to
avoid a possible short scrollable period just after the view is shown.

Bug: 152354290
Change-Id: I7319236d8a6e49a7e017fd54d593ee131dff10a9

src/com/android/launcher3/widget/WidgetsFullSheet.java

@@ -193,6 +193,7 @@ public class WidgetsFullSheet extends BaseWidgetSheet
                     .setDuration(DEFAULT_OPEN_DURATION)
                     .setInterpolator(AnimationUtils.loadInterpolator(
                             getContext(), android.R.interpolator.linear_out_slow_in));
+            mRecyclerView.setLayoutFrozen(true);
             mOpenCloseAnimator.addListener(new AnimatorListenerAdapter() {
                 @Override
                 public void onAnimationEnd(Animator animation) {
@@ -202,7 +203,6 @@ public class WidgetsFullSheet extends BaseWidgetSheet
                 }
             });
             post(() -> {
-                mRecyclerView.setLayoutFrozen(true);
                 mOpenCloseAnimator.start();
                 mContent.animate().alpha(1).setDuration(FADE_IN_DURATION);
             });

tests/tapl/com/android/launcher3/tapl/Widgets.java

@@ -16,6 +16,8 @@
 
 package com.android.launcher3.tapl;
 
+import static com.android.launcher3.tapl.LauncherInstrumentation.WAIT_TIME_MS;
+
 import android.graphics.Point;
 import android.graphics.Rect;
 
@@ -23,6 +25,7 @@ import androidx.test.uiautomator.By;
 import androidx.test.uiautomator.BySelector;
 import androidx.test.uiautomator.Direction;
 import androidx.test.uiautomator.UiObject2;
+import androidx.test.uiautomator.Until;
 
 import com.android.launcher3.tapl.LauncherInstrumentation.GestureScope;
 
@@ -91,6 +94,8 @@ public final class Widgets extends LauncherInstrumentation.VisibleContainer {
         try (LauncherInstrumentation.Closable c = mLauncher.addContextLayer(
                 "getting widget " + labelText + " in widgets list")) {
             final UiObject2 widgetsContainer = verifyActiveContainer();
+            mLauncher.assertTrue("Widgets container didn't become scrollable",
+                    widgetsContainer.wait(Until.scrollable(true), WAIT_TIME_MS));
             final Point displaySize = mLauncher.getRealDisplaySize();
             final BySelector labelSelector = By.clazz("android.widget.TextView").text(labelText);