Add config to disable app tray preview in display size.

Also move some files

Change-Id: I4636fcd81425991acadede0b703e09513c82543c
Fixes: 113374067
Test: robotests

tests/robotests/src/com/android/settings/display/ScreenZoomSettingsTest.java

@@ -0,0 +1,57 @@
+/*
+ * 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.display;
+
+import static com.google.common.truth.Truth.assertThat;
+
+import static org.mockito.Mockito.doReturn;
+import static org.mockito.Mockito.spy;
+
+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;
+import org.robolectric.annotation.Config;
+
+@RunWith(SettingsRobolectricTestRunner.class)
+public class ScreenZoomSettingsTest {
+
+    private ScreenZoomSettings mSettings;
+    private Context mContext;
+
+    @Before
+    public void setUp() {
+        mContext = RuntimeEnvironment.application;
+        mSettings = spy(new ScreenZoomSettings());
+        doReturn(mContext).when(mSettings).getContext();
+    }
+
+    @Test
+    public void getPreviewSampleResIds_default_return3Previews() {
+        assertThat(mSettings.getPreviewSampleResIds()).hasLength(3);
+    }
+
+    @Test
+    @Config(qualifiers = "mcc999")
+    public void getPreviewSampleResIds_extraPreviewDisabled_return1Preview() {
+        assertThat(mSettings.getPreviewSampleResIds()).hasLength(1);
+    }
+}