Can't change user-agent on headless mode

[qphuongl]

Can't change user-agent on headless mode

[canstand]

Can't reproduce it. It worked fine in my test.

func TestHeadlessNew(t *testing.T) {
	b2, err := browserType.Launch(playwright.BrowserTypeLaunchOptions{
		Headless: playwright.Bool(false),
		Args: []string{
			"--disable-extensions", "--disable-images", "--window-size=1920,1080", "--start-maximized", "--headless=new",
		},
		IgnoreDefaultArgs: []string{"--enable-automation", "--no-sandbox", "--mute-audio", "--headless", "--disable-features"},
	})
	require.NoError(t, err)
	defer b2.Close()
	nCtx, err := b2.NewContext(playwright.BrowserNewContextOptions{
		UserAgent: playwright.String("foobar/1.0"),
	})
	require.NoError(t, err)
	defer nCtx.Close()
	nPage, err := nCtx.NewPage()
	require.NoError(t, err)

	resChan := server.WaitForRequestChan("/empty.html")
	_, err = nPage.Goto(server.PREFIX + "/empty.html")
	require.NoError(t, err)
	res := <-resChan
	require.True(t, strings.HasPrefix(res.Header.Get("User-Agent"), "foobar"))
}