Is there an easy way to trigger such a failure? It would be useful such that we can go back to M59, turn off MD Settings, and have a look at how that UI looked, as well as how it was hooked up to the spellchecking backend.

Block redirector.gvt1.com and cache.pack.google.com in your firewall or through your /etc/hosts file.

You can hook in through this Observer interface:

https://cs.chromium.org/chromium/src/chrome/browser/spellchecker/spellcheck_hunspell_dictionary.h?rcl=6e221f71e515a8048a967d8c89a45fe869afce52&l=37

I'm working on showing the errors. I'm including a screenshot of my proposed UI for showing the errors.

The list items in spell check have three states: no errors, one download error and multiple download errors.

No errors looks like the existing UI with a toggle and clickable name that also toggles the use of spell check for that language.

If there is one download error, it will surface on the initial load of the settings. The first line of the error is shown under the name. And a retry button replaces the toggle allowing the user to try downloading the dictionary again.

If after retrying the dictionary download returns an error again, the long error message is shown.

Deleted: spellcheck_download_errors.png 26.4 KB

	spellcheck_download_errors.png 26.4 KB View Download

Looks great!

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/143e0b110ac69781d62ab02bf29c4ac051a3bc8c

commit 143e0b110ac69781d62ab02bf29c4ac051a3bc8c
Author: Esmael El-Moslimany <aee@chromium.org>
Date: Tue Mar 27 03:38:57 2018

Settings WebUI: adding retry dictionary download to languageSettingsPrivate API

Bug:  820456 
Cq-Include-Trybots: master.tryserver.chromium.linux:closure_compilation
Change-Id: Ibaeb426d53d671b54456fd4975a6eebb0934a894
Reviewed-on: https://chromium-review.googlesource.com/969753
Commit-Queue: Esmael El-Moslimany <aee@chromium.org>
Reviewed-by: Michael Giuffrida <michaelpg@chromium.org>
Reviewed-by: Toni Barzic <tbarzic@chromium.org>
Reviewed-by: Jesse Doherty <jwd@chromium.org>
Reviewed-by: Demetrios Papadopoulos <dpapad@chromium.org>
Cr-Commit-Position: refs/heads/master@{#545986}
[modify] https://crrev.com/143e0b110ac69781d62ab02bf29c4ac051a3bc8c/chrome/browser/extensions/api/language_settings_private/language_settings_private_api.cc
[modify] https://crrev.com/143e0b110ac69781d62ab02bf29c4ac051a3bc8c/chrome/browser/extensions/api/language_settings_private/language_settings_private_api.h
[add] https://crrev.com/143e0b110ac69781d62ab02bf29c4ac051a3bc8c/chrome/browser/extensions/api/language_settings_private/language_settings_private_api_unittest.cc
[modify] https://crrev.com/143e0b110ac69781d62ab02bf29c4ac051a3bc8c/chrome/browser/extensions/api/language_settings_private/language_settings_private_delegate.cc
[modify] https://crrev.com/143e0b110ac69781d62ab02bf29c4ac051a3bc8c/chrome/browser/extensions/api/language_settings_private/language_settings_private_delegate.h
[add] https://crrev.com/143e0b110ac69781d62ab02bf29c4ac051a3bc8c/chrome/browser/extensions/api/language_settings_private/language_settings_private_delegate_unittest.cc
[modify] https://crrev.com/143e0b110ac69781d62ab02bf29c4ac051a3bc8c/chrome/common/extensions/api/language_settings_private.idl
[modify] https://crrev.com/143e0b110ac69781d62ab02bf29c4ac051a3bc8c/chrome/test/BUILD.gn
[modify] https://crrev.com/143e0b110ac69781d62ab02bf29c4ac051a3bc8c/extensions/browser/extension_function_histogram_value.h
[modify] https://crrev.com/143e0b110ac69781d62ab02bf29c4ac051a3bc8c/third_party/closure_compiler/externs/language_settings_private.js
[modify] https://crrev.com/143e0b110ac69781d62ab02bf29c4ac051a3bc8c/tools/metrics/histograms/enums.xml

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/3f225c8b741e8a079f6a3d3ae58ecf1b727623ac

commit 3f225c8b741e8a079f6a3d3ae58ecf1b727623ac
Author: Esmael El-Moslimany <aee@chromium.org>
Date: Thu Mar 29 23:27:32 2018

Settings WebUI: show spell check dictionary download error and retry

Bug:  820456 
Cq-Include-Trybots: master.tryserver.chromium.linux:closure_compilation
Change-Id: I91afc303b1e5b5c03e12b7ccaef7a2d8fd49ef61
Reviewed-on: https://chromium-review.googlesource.com/982159
Commit-Queue: Esmael El-Moslimany <aee@chromium.org>
Reviewed-by: Hector Carmona <hcarmona@chromium.org>
Reviewed-by: Demetrios Papadopoulos <dpapad@chromium.org>
Cr-Commit-Position: refs/heads/master@{#547015}
[modify] https://crrev.com/3f225c8b741e8a079f6a3d3ae58ecf1b727623ac/chrome/app/settings_strings.grdp
[modify] https://crrev.com/3f225c8b741e8a079f6a3d3ae58ecf1b727623ac/chrome/browser/resources/settings/languages_page/languages.js
[modify] https://crrev.com/3f225c8b741e8a079f6a3d3ae58ecf1b727623ac/chrome/browser/resources/settings/languages_page/languages_page.html
[modify] https://crrev.com/3f225c8b741e8a079f6a3d3ae58ecf1b727623ac/chrome/browser/resources/settings/languages_page/languages_page.js
[modify] https://crrev.com/3f225c8b741e8a079f6a3d3ae58ecf1b727623ac/chrome/browser/resources/settings/languages_page/languages_types.js
[modify] https://crrev.com/3f225c8b741e8a079f6a3d3ae58ecf1b727623ac/chrome/browser/resources/settings/people_page/easy_unlock_turn_off_dialog.js
[modify] https://crrev.com/3f225c8b741e8a079f6a3d3ae58ecf1b727623ac/chrome/browser/ui/webui/settings/md_settings_localized_strings_provider.cc
[modify] https://crrev.com/3f225c8b741e8a079f6a3d3ae58ecf1b727623ac/chrome/test/data/webui/settings/fake_language_settings_private.js
[modify] https://crrev.com/3f225c8b741e8a079f6a3d3ae58ecf1b727623ac/chrome/test/data/webui/settings/languages_page_tests.js
[modify] https://crrev.com/3f225c8b741e8a079f6a3d3ae58ecf1b727623ac/third_party/closure_compiler/interfaces/language_settings_private_interface.js

 Issue 622393  has been merged into this issue.