Chrome Version: 63.3219

What steps will reproduce the problem?
(1) Visit chrome://settings/passwords
(2) Right-click on the dots of an obscured password

Observe: A "Generate Password" command is present in the context menu.

Expect: No command, because the field is readonly.

We should probably check to see if the field is readonly before adding the menu item inside RenderViewContextMenu::AppendPasswordItems [1].

It's also not clear to me whether we should offer the Generate Password command on chrome:// pages.

[1] https://cs.chromium.org/chromium/src/chrome/browser/renderer_context_menu/render_view_context_menu.cc?l=1519&rcl=e494fc874f455309c9b025727b40a837bf713971