Add lock-to-app to settings

Lock-to-app when disabled shows some instructions about how to
enable it and use it.

When enabled shows an option of use lock screen, which controls
whether the device is locked when exiting lock-to-app.  Turning
on use lock screen requires that the device have some security
challenge.

Bug: 15759649
Change-Id: I6188243e03fb0c85bdfdbc32a23ad486296a34f9

res/layout/lock_to_app_instructions.xml

@@ -0,0 +1,74 @@
+<?xml version="1.0" encoding="utf-8"?>
+<!--
+/*
+** Copyright 2014, 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.
+*/
+-->
+
+<FrameLayout xmlns:android="http://schemas.android.com/apk/res/android"
+    android:layout_width="match_parent"
+    android:layout_height="match_parent">
+
+    <LinearLayout
+        android:id="@+id/instructions_area"
+        android:layout_width="match_parent"
+        android:layout_height="match_parent"
+        android:orientation="vertical"
+        android:paddingLeft="@dimen/switchbar_subsettings_margin_start"
+        android:paddingRight="@dimen/screen_margin_sides">
+
+        <TextView
+            android:layout_width="match_parent"
+            android:layout_height="wrap_content"
+            android:layout_alignParentTop="true"
+            android:paddingTop="@dimen/lock_to_app_textview_padding"
+            android:text="@string/lock_to_app_description"
+            android:textAppearance="@style/TextAppearance.Medium"
+            />
+
+        <TextView
+            android:layout_width="wrap_content"
+            android:layout_height="wrap_content"
+            android:paddingTop="@dimen/lock_to_app_textview_padding"
+            android:text="@string/lock_to_app_start_step1"
+            android:textAppearance="@style/TextAppearance.Medium"
+            />
+
+        <TextView
+            android:layout_width="wrap_content"
+            android:layout_height="wrap_content"
+            android:paddingTop="@dimen/lock_to_app_textview_padding"
+            android:text="@string/lock_to_app_start_step2"
+            android:textAppearance="@style/TextAppearance.Medium"
+            />
+
+        <TextView
+            android:id="@+id/lock_to_app_start_step3"
+            android:layout_width="wrap_content"
+            android:layout_height="wrap_content"
+            android:paddingBottom="@dimen/lock_to_app_textview_padding"
+            android:paddingTop="@dimen/lock_to_app_textview_padding"
+            android:text="@string/lock_to_app_start_step3"
+            android:textAppearance="@style/TextAppearance.Medium"
+            />
+
+    </LinearLayout>
+
+    <ListView
+        android:id="@android:id/list"
+        android:layout_width="match_parent"
+        android:layout_height="match_parent"/>
+
+</FrameLayout>