app/src/main/res/drawable/ic_dropdown_16.xml
<vector android:height="16dp" android:tint="?attr/colorControlNormal"
android:viewportHeight="24" android:viewportWidth="24"
android:width="16dp" xmlns:android="http://schemas.android.com/apk/res/android">
<path android:fillColor="@android:color/white" android:pathData="M7,10l5,5 5,-5z"/>
</vector>