[BUG] Search suggestion from omnibox don't work after I delete default search engines

[Admini]

There is no suggestion for all customized search engines, because Chromium doesn't set "suggestion_url" parameter automatically.
You have to manually edit the file "User Data\Default\Preferences"(open with text editor, remember backup it first)
And copy the value of "suggestions_url" of default Google to your customized one.
[The value of suggestion_url of default Google is probably:
{google:baseSuggestURL}search?{google:searchFieldtrialParameter}client={google:suggestClient}&gs_ri={google:suggestRid}&xssi=t&q={searchTerms}&{google:inputType}{google:cursorPosition}{google:currentPageUrl}{google:pageClassification}{google:searchVersion}{google:sessionToken}{google:prefetchQuery}sugkey={google:suggestAPIKeyParameter}
]