工具栏箭头在NavigationDrawer的PreferenceFragment中不起作用

public class MainActivity extends AppCompatActivity {

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

        Toolbar toolbar = findViewById(R.id.toolbar);
        setSupportActionBar(toolbar);

        // 显示箭头按钮
        ActionBar actionBar = getSupportActionBar();
        if (actionBar != null) {
            actionBar.setDisplayHomeAsUpEnabled(true);
        }

        // 加载PreferenceFragment
        getFragmentManager().beginTransaction()
                .replace(R.id.content_frame, new MyPreferenceFragment())
                .commit();
    }

    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        getMenuInflater().inflate(R.menu.menu_main, menu);
        return true;
    }

    @Override
    public boolean onOptionsItemSelected(MenuItem item) {
        int id = item.getItemId();

        if (id == android.R.id.home) {
            // 点击了箭头按钮
            getSupportFragmentManager().popBackStack();
            return true;
        }

        return super.onOptionsItemSelected(item);
    }

    public static class MyPreferenceFragment extends PreferenceFragment {

        @Override
        public void onCreate(Bundle savedInstanceState) {
            super.onCreate(savedInstanceState);
            setHasOptionsMenu(true);
            addPreferencesFromResource(R.xml.preferences);
        }
    }
}