Set track drawable to null to remove grey track.

        <item name="android:actionOverflowButtonStyle">@style/ContactsActionBarOverflowQP</item>

        <item name="android:actionModeCloseDrawable">@drawable/ic_close_lt</item>

        <item name="android:fastScrollThumbDrawable">@drawable/fastscroll_thumb</item>

        <item name="android:fastScrollTrackDrawable">@null</item>

        <item name="android:textColorPrimary">@color/primary_text_color</item>

        <item name="android:textColorSecondary">@color/secondary_text_color</item>

        <item name="android:icon">@android:color/transparent</item>