use system color for list view selected background color

MyTracks/res/drawable/activated_background_mytracks.xml

@@ -1,20 +0,0 @@
-<?xml version="1.0" encoding="utf-8"?>
-<!--
-Copyright 2013 Google Inc.
-
-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.
--->
-<selector xmlns:android="http://schemas.android.com/apk/res/android">
-  <item android:drawable="@drawable/list_selector_background_mytracks" android:state_activated="true"/>
-  <item android:drawable="@android:color/transparent"/>
-</selector>

MyTracks/res/values-v11/styles.xml

@@ -34,7 +34,7 @@ limitations under the License.
     <item name="android:measureWithLargestChild">true</item>
   </style>
   <style name="ListItem">
-    <item name="android:background">@drawable/activated_background_mytracks</item>
+    <item name="android:background">?android:attr/activatedBackgroundIndicator</item>
   </style>
   <style name="ThemeSelector" parent="android:Theme.Holo">
     <item name="android:actionBarStyle">@style/ActionBarStyle.MyTracks</item>