Browser test for guest signin button.

chrome/browser/chromeos/login/webview_login_browsertest.cc

Index: chrome/browser/chromeos/login/webview_login_browsertest.cc
diff --git a/chrome/browser/chromeos/login/webview_login_browsertest.cc b/chrome/browser/chromeos/login/webview_login_browsertest.cc
index b7d3caa4a681606f2accfe80050ba77feddba623..4e1fa1f2b5e887240d20430bacb1b616f844fa16 100644
--- a/chrome/browser/chromeos/login/webview_login_browsertest.cc
+++ b/chrome/browser/chromeos/login/webview_login_browsertest.cc
@@ -79,4 +79,11 @@ IN_PROC_BROWSER_TEST_F(WebviewLoginTest, BackButton) {
   session_start_waiter.Wait();
 }
 
+IN_PROC_BROWSER_TEST_F(WebviewLoginTest, AllowGuest) {
+  WaitForGaiaPageLoad();
+  JsExpect("!$('guest-user-header-bar-item').hidden");
+  chromeos::CrosSettings::Get()->SetBoolean(kAccountsPrefAllowGuest, false);
+  JsExpect("$('guest-user-header-bar-item').hidden");
+}
+
 }  // namespace chromeos