[Autofill/Autocomplete Feature] Substring matching instead of prefix matching.

components/autofill/core/browser/personal_data_manager.cc

Index: components/autofill/core/browser/personal_data_manager.cc
diff --git a/components/autofill/core/browser/personal_data_manager.cc b/components/autofill/core/browser/personal_data_manager.cc
index ca41fd5b5cf8a22f8287fdc02fb3bdc74b62855d..d01745027ad5044bbc2ec3123a11d39b8f985c33 100644
--- a/components/autofill/core/browser/personal_data_manager.cc
+++ b/components/autofill/core/browser/personal_data_manager.cc
@@ -800,6 +800,7 @@ std::vector<Suggestion> PersonalDataManager::GetProfileSuggestions(
       matched_profiles.push_back(profile);
       suggestions.push_back(Suggestion(value));
       suggestions.back().backend_id = profile->guid();
+      suggestions.back().match_start = field_contents.size();
     }
   }
 
@@ -916,6 +917,7 @@ std::vector<Suggestion> PersonalDataManager::GetCreditCardSuggestions(
     suggestion->value = credit_card->GetInfo(type, app_locale_);
     suggestion->icon = base::UTF8ToUTF16(credit_card->type());
     suggestion->backend_id = credit_card->guid();
+    suggestion->match_start = field_contents.size();
 
     // If the value is the card number, the label is the expiration date.
     // Otherwise the label is the card number, or if that is empty the