Add toolbar to preference fragments

Test: Manually
Change-Id: Ifd24aacb4e8fbd4806a44ec004dfc322427aa3d5
diff --git a/car-ui-lib/res/layout/car_ui_preference_fragment.xml b/car-ui-lib/res/layout/car_ui_preference_fragment.xml
index b70bfa5..766196d 100644
--- a/car-ui-lib/res/layout/car_ui_preference_fragment.xml
+++ b/car-ui-lib/res/layout/car_ui_preference_fragment.xml
@@ -15,10 +15,18 @@
     limitations under the License.
 -->
 
-<FrameLayout
+<LinearLayout
     xmlns:android="http://schemas.android.com/apk/res/android"
+    xmlns:app="http://schemas.android.com/apk/res-auto"
     android:layout_width="match_parent"
-    android:layout_height="match_parent">
+    android:layout_height="match_parent"
+    android:orientation="vertical">
+
+    <com.android.car.ui.toolbar.Toolbar
+        android:layout_width="match_parent"
+        android:layout_height="wrap_content"
+        android:id="@+id/toolbar"
+        app:state="subpage"/>
 
     <FrameLayout
         android:id="@android:id/list_container"
@@ -31,4 +39,4 @@
             android:scrollbars="none"/>
     </FrameLayout>
 
-</FrameLayout>
+</LinearLayout>