如何在ActionBar上为图标添加边距？

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="horizontal"
    android:gravity="center_vertical">

    <ImageView
        android:id="@+id/action_bar_icon"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:src="@drawable/ic_action_bar_icon"
        android:paddingStart="8dp"
        android:paddingEnd="8dp" />

    <TextView
        android:id="@+id/action_bar_title"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="ActionBar Title"
        android:textColor="#FFFFFF"
        android:textSize="18sp" />

</LinearLayout>

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);

    ActionBar actionBar = getSupportActionBar();
    actionBar.setDisplayOptions(ActionBar.DISPLAY_SHOW_CUSTOM);
    actionBar.setCustomView(R.layout.action_bar_custom);
}