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

components/password_manager/core/browser/password_autofill_manager.cc

Index: components/password_manager/core/browser/password_autofill_manager.cc
diff --git a/components/password_manager/core/browser/password_autofill_manager.cc b/components/password_manager/core/browser/password_autofill_manager.cc
index a7a71085d9f864199eab2892a8f79ac65636e17c..bc88d88b4765103e4a9ef14bdfeeb33e97eca2d3 100644
--- a/components/password_manager/core/browser/password_autofill_manager.cc
+++ b/components/password_manager/core/browser/password_autofill_manager.cc
@@ -72,6 +72,7 @@ void GetSuggestions(const autofill::PasswordFormFillData& fill_data,
         ReplaceEmptyUsername(fill_data.username_field.value));
     suggestion.label = GetHumanReadableRealm(fill_data.preferred_realm);
     suggestion.frontend_id = autofill::POPUP_ITEM_ID_PASSWORD_ENTRY;
+    suggestion.match_start = current_username.size();
     suggestions->push_back(suggestion);
   }
 
@@ -80,6 +81,7 @@ void GetSuggestions(const autofill::PasswordFormFillData& fill_data,
       autofill::Suggestion suggestion(ReplaceEmptyUsername(login.first));
       suggestion.label = GetHumanReadableRealm(login.second.realm);
       suggestion.frontend_id = autofill::POPUP_ITEM_ID_PASSWORD_ENTRY;
+      suggestion.match_start = current_username.size();
       suggestions->push_back(suggestion);
     }
   }
@@ -92,6 +94,7 @@ void GetSuggestions(const autofill::PasswordFormFillData& fill_data,
             ReplaceEmptyUsername(usernames.second[i]));
         suggestion.label = GetHumanReadableRealm(usernames.first.realm);
         suggestion.frontend_id = autofill::POPUP_ITEM_ID_PASSWORD_ENTRY;
+        suggestion.match_start = current_username.size();
         suggestions->push_back(suggestion);
       }
     }
@@ -131,16 +134,16 @@ bool PasswordAutofillManager::FillSuggestion(int key,
   return false;
 }
 
-bool PasswordAutofillManager::PreviewSuggestion(
-    int key,
-    const base::string16& username) {
+bool PasswordAutofillManager::PreviewSuggestion(int key,
+                                                const base::string16& username,
+                                                size_t match_start) {
   autofill::PasswordFormFillData fill_data;
   autofill::PasswordAndRealm password_and_realm;
   if (FindLoginInfo(key, &fill_data) &&
       GetPasswordAndRealmForUsername(
           username, fill_data, &password_and_realm)) {
     password_manager_driver_->PreviewSuggestion(
-        username, password_and_realm.password);
+        username, password_and_realm.password, match_start);
     return true;
   }
   return false;
@@ -203,8 +206,9 @@ bool PasswordAutofillManager::FillSuggestionForTest(
 
 bool PasswordAutofillManager::PreviewSuggestionForTest(
     int key,
-    const base::string16& username) {
-  return PreviewSuggestion(key, username);
+    const base::string16& username,
+    size_t match_start) {
+  return PreviewSuggestion(key, username, match_start);
 }
 
 void PasswordAutofillManager::OnPopupShown() {
@@ -214,9 +218,10 @@ void PasswordAutofillManager::OnPopupHidden() {
 }
 
 void PasswordAutofillManager::DidSelectSuggestion(const base::string16& value,
-                                                  int identifier) {
+                                                  int identifier,
+                                                  size_t match_start) {
   ClearPreviewedForm();
-  bool success = PreviewSuggestion(form_data_key_, value);
+  bool success = PreviewSuggestion(form_data_key_, value, match_start);
   DCHECK(success);
 }