Add 'x' button to the signin promo in the password bubble on Mac.

chrome/browser/ui/cocoa/passwords/signin_promo_view_controller_unittest.mm

 // Copyright 2016 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #import "chrome/browser/ui/cocoa/passwords/signin_promo_view_controller.h"
 
 #include "base/metrics/field_trial.h"
 #import "chrome/browser/ui/cocoa/passwords/base_passwords_controller_test.h"
 #include "chrome/browser/ui/passwords/manage_passwords_ui_controller_mock.h"
 #include "components/password_manager/core/browser/password_bubble_experiment.h"
@@ skipping 56 matching lines @@
   EXPECT_TRUE([delegate() dismissed]);
 }
 
 TEST_F(SignInPromoViewControllerTest, ClickNo) {
   EXPECT_CALL(*ui_controller(), NavigateToChromeSignIn()).Times(0);
   [controller().noButton performClick:nil];
 
   EXPECT_TRUE([delegate() dismissed]);
 }
 
+TEST_F(SignInPromoViewControllerTest, ClickClose) {
+  EXPECT_CALL(*ui_controller(), NavigateToChromeSignIn()).Times(0);
+  [controller().closeButton performClick:nil];
+
+  EXPECT_TRUE([delegate() dismissed]);
+}
+
 TEST_F(SignInPromoViewControllerTest, CloseBubbleAndHandleClick) {
   // A user may press mouse down, some navigation closes the bubble, mouse up
   // still sends the action.
   EXPECT_CALL(*ui_controller(), NavigateToChromeSignIn()).Times(0);
   [delegate() setModel:nil];
   [controller().signInButton performClick:nil];
   [controller().noButton performClick:nil];
+  [controller().closeButton performClick:nil];
 }
 
 }  // namespace