Don't try to create a verbatim match with an empty input.

components/omnibox/browser/verbatim_match.h

Index: components/omnibox/browser/verbatim_match.h
diff --git a/components/omnibox/browser/verbatim_match.h b/components/omnibox/browser/verbatim_match.h
index 05573b15d4715da0cae1a2d59f88fe848193ec79..9b4f0b6c2b2edc1aadac1905db7325fef2ead973 100644
--- a/components/omnibox/browser/verbatim_match.h
+++ b/components/omnibox/browser/verbatim_match.h
@@ -15,9 +15,10 @@ class HistoryURLProvider;
 
 // Returns a verbatim match for input.text() with a relevance of
 // |verbatim_relevance|. If |verbatim_relevance| is negative then a default
-// value is used.  If the desired |destination_url| is already known and a
+// value is used. If the desired |destination_url| is already known and a
 // |history_url_provider| is also provided, this may be more efficient (see
 // implementation for details) than the default code path.
+// input.text() must not be empty.
 AutocompleteMatch VerbatimMatchForURL(
     AutocompleteProviderClient* client,
     const AutocompleteInput& input,