android add activity parent manifest

1<!-- The main/home activity (it has no parent activity) -->
2    <activity
3        android:name="com.example.app_name.A" ...>
4        ...
5    </activity>
6    <!-- A child of the main activity -->
7    <activity
8        android:name=".B"
9        android:label="B"
10        android:parentActivityName="com.example.app_name.A" >
11        <!-- Parent activity meta-data to support 4.0 and lower -->
12        <meta-data
13            android:name="android.support.PARENT_ACTIVITY"
14            android:value="com.example.app_name.A" />
15    </activity>