Add smart battery page for battery settings

This page contains prefs for smart battery and app restriction.

Bug: 71502850
Test: RunSettingsRoboTests

Change-Id: I194af30cbc7b2496b10098fcb67f1116e0722310

res/layout/smart_battery_header.xml

@@ -0,0 +1,30 @@
+<?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.
+  -->
+
+<!-- Entity header -->
+<LinearLayout
+    xmlns:android="http://schemas.android.com/apk/res/android"
+    android:id="@+id/entity_header"
+    style="@style/EntityHeader"
+    android:layout_width="match_parent"
+    android:layout_height="match_parent"
+    android:minHeight="200dp"
+    android:paddingBottom="32dp"
+    android:paddingStart="@dimen/preference_no_icon_padding_start"
+    android:paddingTop="24dp">
+
+</LinearLayout>