Prevent the Online Reauth window from opening twice.

chrome/browser/ui/cocoa/profiles/user_manager_mac.mm

Index: chrome/browser/ui/cocoa/profiles/user_manager_mac.mm
diff --git a/chrome/browser/ui/cocoa/profiles/user_manager_mac.mm b/chrome/browser/ui/cocoa/profiles/user_manager_mac.mm
index 3a34663b15e1c9b00cebcb53b63c959d42c25f08..0b989afe111fffc9c86871b79e96ffde765a3992 100644
--- a/chrome/browser/ui/cocoa/profiles/user_manager_mac.mm
+++ b/chrome/browser/ui/cocoa/profiles/user_manager_mac.mm
@@ -365,15 +365,17 @@ class ReauthDialogDelegate : public UserManager::ReauthDialogObserver,
 }
 
 - (void)showReauthDialogWithProfile:(Profile*)profile email:(std::string)email {
-  reauth_window_controller_.reset(
-      [[ReauthDialogWindowController alloc]
-          initWithProfile:profile
-                    email:email
-              webContents:webContents_.get()]);
+  if (!reauth_window_controller_) {
+    reauth_window_controller_.reset(
+        [[ReauthDialogWindowController alloc]
+            initWithProfile:profile
+                      email:email
+                webContents:webContents_.get()]);
+  }
 }
 
 - (void)closeReauthDialog {
-  [reauth_window_controller_ close];
+  reauth_window_controller_.reset();
 }
 
 @end