The root-cause seems to be the following: For manual fallback purposes we show the "Show all saved passwords" menu item whenever a user right clicks on a password field. After a click on that menu item, chrome://settings/passwords is opened in a new tab.

However, in this case, we are already on chrome://settings/passwords and nothing happens. I see two possible solutions:

1) Don't make the entries on chrome://settings/password <input>s of type=password

2) Disable adding the context menu entry on chrome://settings/passwords (possibly even on all chrome:// pages).

I don't think (1) is a good solution, as these in-fact are password fields and the markup should reflect it. So I think we should go with option (2).

dvadym@, do you mind taking a look at this? You have worked with context menu entries in the past.

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/d37da64fcceee283713d649aa8733e669601f5e8

commit d37da64fcceee283713d649aa8733e669601f5e8
Author: Vasilii Sukhanov <vasilii@chromium.org>
Date: Mon Sep 10 14:07:42 2018

Don't show "Show all passwords" context menu item in the guest mode and on
Chrome internal pages.

Basically it should not appear if password filling is disabled. In addition the
guest mode should also suppress the item as it leads to nowhere.

Bug:  865917 
Change-Id: Id260341e381ab99d364daf8819f7f07cd350b141
Reviewed-on: https://chromium-review.googlesource.com/1205030
Commit-Queue: Vasilii Sukhanov <vasilii@chromium.org>
Reviewed-by: Vadym Doroshenko <dvadym@chromium.org>
Reviewed-by: Istiaque Ahmed <lazyboy@chromium.org>
Cr-Commit-Position: refs/heads/master@{#589899}
[modify] https://crrev.com/d37da64fcceee283713d649aa8733e669601f5e8/chrome/browser/password_manager/chrome_password_manager_client.cc
[modify] https://crrev.com/d37da64fcceee283713d649aa8733e669601f5e8/chrome/browser/password_manager/chrome_password_manager_client_unittest.cc
[modify] https://crrev.com/d37da64fcceee283713d649aa8733e669601f5e8/chrome/browser/renderer_context_menu/render_view_context_menu.cc
[modify] https://crrev.com/d37da64fcceee283713d649aa8733e669601f5e8/chrome/browser/renderer_context_menu/render_view_context_menu_unittest.cc
[modify] https://crrev.com/d37da64fcceee283713d649aa8733e669601f5e8/components/password_manager/core/browser/password_autofill_manager.cc
[modify] https://crrev.com/d37da64fcceee283713d649aa8733e669601f5e8/components/password_manager/core/browser/password_manager_util.cc
[modify] https://crrev.com/d37da64fcceee283713d649aa8733e669601f5e8/components/password_manager/core/browser/password_manager_util.h
[modify] https://crrev.com/d37da64fcceee283713d649aa8733e669601f5e8/components/password_manager/core/common/password_manager_features.cc
[modify] https://crrev.com/d37da64fcceee283713d649aa8733e669601f5e8/components/password_manager/core/common/password_manager_features.h