Make vertical divider darker for two_target preference

Change-Id: I64135de13e7e5064f1df22d5aa9626eb59b8e92c
Fix: 37475391
Test: visual

packages/SettingsLib/res/drawable/list_divider_dark.xml

@@ -0,0 +1,24 @@
+<?xml version="1.0" encoding="utf-8"?>
+<!--
+  Copyright (C) 2017 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.
+  -->
+
+<shape
+    xmlns:android="http://schemas.android.com/apk/res/android">
+    <solid android:color="#64000000" />
+    <size
+        android:height="1dp"
+        android:width="1dp" />
+</shape>

packages/SettingsLib/res/layout/preference_two_target_divider.xml

@@ -27,5 +27,5 @@
     <View
         android:layout_width="1dp"
         android:layout_height="match_parent"
-        android:background="?android:attr/dividerVertical" />
+        android:background="@drawable/list_divider_dark" />
 </LinearLayout>