Add a switchbar to turn off multi-user feature entirely

Change-Id: Ibf88bf37899af5065c68aeb2337acd4ee48bc13c
Fixes: 72319180
Test: robotest on new controller. Manual test on UserSettings fragment.

tests/robotests/src/com/android/settings/users/MultiUserFooterPreferenceControllerTest.java

@@ -0,0 +1,59 @@
+/*
+ * Copyright (C) 2018 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.users;
+
+import static com.android.settings.core.BasePreferenceController.AVAILABLE_UNSEARCHABLE;
+import static com.android.settings.core.BasePreferenceController.DISABLED_FOR_USER;
+import static com.google.common.truth.Truth.assertThat;
+
+import android.content.Context;
+
+import com.android.settings.testutils.SettingsRobolectricTestRunner;
+
+import org.junit.Before;
+import org.junit.Test;
+import org.junit.runner.RunWith;
+import org.robolectric.RuntimeEnvironment;
+
+@RunWith(SettingsRobolectricTestRunner.class)
+public class MultiUserFooterPreferenceControllerTest {
+
+    private Context mContext;
+    private MultiUserFooterPreferenceController mController;
+
+    @Before
+    public void setUp() {
+        mContext = RuntimeEnvironment.application;
+        mController = new MultiUserFooterPreferenceController(mContext);
+    }
+
+    @Test
+    public void getAvailabilityStatus_multiUserOff_shouldReturnEnabled() {
+        mController.mUserCaps.mEnabled = true;
+        mController.mUserCaps.mUserSwitcherEnabled = false;
+
+        assertThat(mController.getAvailabilityStatus()).isEqualTo(AVAILABLE_UNSEARCHABLE);
+    }
+
+    @Test
+    public void getAvailabilityStatus_multiUserOn_shouldReturnDisabled() {
+        mController.mUserCaps.mEnabled = true;
+        mController.mUserCaps.mUserSwitcherEnabled = true;
+
+        assertThat(mController.getAvailabilityStatus()).isEqualTo(DISABLED_FOR_USER);
+    }
+}