Add a new widget MasterCheckBoxPreference.

This is similar to the master switch preference, but instead of the
toggle button, it provides a checkbox as the preference widget.

Change-Id: Ic2392f6a828298ab85494e7dd127fd2d787ce121
Fixes: 71603100
Test: make RunSettingsRoboTests

res/layout/preference_widget_master_checkbox.xml

@@ -0,0 +1,26 @@
+<?xml version="1.0" encoding="utf-8"?>
+<!--
+  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.
+  -->
+
+<CheckBox
+    xmlns:android="http://schemas.android.com/apk/res/android"
+    android:id="@+id/checkboxWidget"
+    android:layout_width="match_parent"
+    android:layout_height="match_parent"
+    android:gravity="center"
+    android:layout_marginStart="?android:attr/listPreferredItemPaddingEnd"
+    android:layout_marginEnd="?android:attr/listPreferredItemPaddingEnd"
+    android:clickable="false" />