Not use NEW_TASKS for Wallpaper & style's 2-pane UX

Refine launch mode to support 2-pane UX for Settings.

Bug: 197609643
Test: make RunSettingsRoboTests
Change-Id: I5212bbcf8c512fac571284379a29cf487f387c5a

tests/robotests/src/com/android/settings/testutils/shadow/ShadowActivityEmbeddingUtils.java

@@ -0,0 +1,41 @@
+/*
+ * Copyright (C) 2021 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.android.settings.testutils.shadow;
+
+import android.content.Context;
+
+import com.android.settings.activityembedding.ActivityEmbeddingUtils;
+
+import org.robolectric.annotation.Implementation;
+import org.robolectric.annotation.Implements;
+
+/**
+ * Shadow class for {@link ActivityEmbeddingUtils} to test embedding activity features.
+ */
+@Implements(ActivityEmbeddingUtils.class)
+public class ShadowActivityEmbeddingUtils {
+    private static boolean sIsEmbeddingActivityEnabled;
+
+    @Implementation
+    public static boolean isEmbeddingActivityEnabled(Context context) {
+        return sIsEmbeddingActivityEnabled;
+    }
+
+    public static void setIsEmbeddingActivityEnabled(boolean isEmbeddingActivityEnabled) {
+        sIsEmbeddingActivityEnabled = isEmbeddingActivityEnabled;
+    }
+}