Autofill username when the user interacts with the password field.

components/autofill/content/renderer/password_autofill_agent.cc

 // Copyright 2013 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "components/autofill/content/renderer/password_autofill_agent.h"
 
 #include <stddef.h>
 
 #include <memory>
 #include <string>
@@ skipping 288 matching lines @@
     return username1 == username2;
   return FieldIsSuggestionSubstringStartingOnTokenBoundary(username1, username2,
                                                            true);
 }
 
 // Returns |true| if the given element is editable. Otherwise, returns |false|.
 bool IsElementAutocompletable(const blink::WebInputElement& element) {
   return IsElementEditable(element);
 }
 
+bool IsUsernameAmendable(const blink::WebInputElement& username_element,

[pkalinnikov, 2017/05/24 10:43:31]

nit: Add comment?

+                         bool is_password_field_selected) {
+  return !username_element.IsNull() &&
+         IsElementAutocompletable(username_element) &&
+         (!is_password_field_selected || username_element.IsAutofilled() ||
+          username_element.Value().IsEmpty());
+}
+
 // Return true if either password_value or new_password_value is not empty and
 // not default.
 bool FormContainsNonDefaultPasswordValue(const PasswordForm& password_form) {
   return (!password_form.password_value.empty() &&
           !password_form.password_value_is_default) ||
       (!password_form.new_password_value.empty() &&
        !password_form.new_password_value_is_default);
 }
 
 // Log a message including the name, method and action of |form|.
@@ skipping 472 matching lines @@
   if (!FindPasswordInfoForElement(*element, &username_element,
                                   &password_element, &password_info) ||
       !IsElementAutocompletable(password_element)) {
     return false;
   }
 
   password_info->password_was_edited_last = false;
   if (element->IsPasswordField()) {
     password_info->password_field_suggestion_was_accepted = true;
     password_info->password_field = password_element;
-  } else if (!username_element.IsNull() &&
-             IsElementAutocompletable(username_element)) {
+  }
+
+  if (IsUsernameAmendable(username_element, element->IsPasswordField())) {
     username_element.SetAutofillValue(blink::WebString::FromUTF16(username));
     username_element.SetAutofilled(true);
     UpdateFieldValueAndPropertiesMaskMap(username_element, &username,
                                          FieldPropertiesFlags::AUTOFILLED,
                                          &field_value_and_properties_map_);
   }
 
   password_element.SetAutofillValue(blink::WebString::FromUTF16(password));
   password_element.SetAutofilled(true);
   UpdateFieldValueAndPropertiesMaskMap(password_element, &password,
@@ skipping 19 matching lines @@
   blink::WebInputElement username_element;
   blink::WebInputElement password_element;
   PasswordInfo* password_info;
 
   if (!FindPasswordInfoForElement(*element, &username_element,
                                   &password_element, &password_info) ||
       !IsElementAutocompletable(password_element)) {
     return false;
   }
 
-  if (!element->IsPasswordField() && !username_element.IsNull() &&
-      IsElementAutocompletable(username_element)) {
+  if (IsUsernameAmendable(username_element, element->IsPasswordField())) {
     if (username_query_prefix_.empty())
       username_query_prefix_ = username_element.Value().Utf16();
 
     was_username_autofilled_ = username_element.IsAutofilled();
     username_element.SetSuggestedValue(username);
     username_element.SetAutofilled(true);
     form_util::PreviewSuggestion(username_element.SuggestedValue().Utf16(),
                                  username_query_prefix_, &username_element);
   }
   was_password_autofilled_ = password_element.IsAutofilled();
   password_element.SetSuggestedValue(password);
   password_element.SetAutofilled(true);
 
   return true;
 }
 
 bool PasswordAutofillAgent::DidClearAutofillSelection(
     const blink::WebFormControlElement& control_element) {
   const blink::WebInputElement* element = ToWebInputElement(&control_element);
   if (!element)
     return false;
 
   blink::WebInputElement username_element;
   blink::WebInputElement password_element;
   PasswordInfo* password_info;
 
   if (!FindPasswordInfoForElement(*element, &username_element,
-                                  &password_element, &password_info))
+                                  &password_element, &password_info)) {
     return false;
+  }
 
   ClearPreview(&username_element, &password_element);
   return true;
 }
 
 bool PasswordAutofillAgent::FindPasswordInfoForElement(
     const blink::WebInputElement& element,
     blink::WebInputElement* username_element,
     blink::WebInputElement* password_element,
     PasswordInfo** password_info) {
@@ skipping 841 matching lines @@
 PasswordAutofillAgent::GetPasswordManagerDriver() {
   if (!password_manager_driver_) {
     render_frame()->GetRemoteInterfaces()->GetInterface(
         mojo::MakeRequest(&password_manager_driver_));
   }
 
   return password_manager_driver_;
 }
 
 }  // namespace autofill