Passwords: Re-fill fields when the autofill suggestions are updated

Bug: 1016712
Change-Id: Iaf86d87d3f53c6446199897f4a2482c49ef5ff2d
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1900996Reviewed-by: Vadym Doroshenko <dvadym@chromium.org>
Commit-Queue: Marc Treib <treib@chromium.org>
Cr-Commit-Position: refs/heads/master@{#713372}

chrome/browser/password_manager/password_manager_browsertest.cc

@@ -3900,9 +3900,8 @@ IN_PROC_BROWSER_TEST_F(PasswordManagerBrowserTest,
   EXPECT_EQ(base::ASCIIToUTF16("user"), controller->GetElidedValueAt(0));
   EXPECT_NE(base::ASCIIToUTF16("admin"), controller->GetElidedValueAt(1));
 
-  // TODO(crbug.com/1004777): Here the username_field should get re-filled with
-  // "user" instead of "admin".
-  // WaitForElementValue("username_field", "user");
+  // The username_field should get re-filled with "user" instead of "admin".
+  WaitForElementValue("username_field", "user");
 
   // Delete all the credentials.
   password_store->RemoveLogin(user_form);

components/autofill/content/renderer/password_autofill_agent.cc

@@ -1558,6 +1558,7 @@ bool PasswordAutofillAgent::FillUserNameAndPassword(
                                         possible_email_domain) ||
          fill_data.username_may_use_prefilled_placeholder);
     if (!username_element.Value().IsEmpty() &&
+        username_element.GetAutofillState() == WebAutofillState::kNotFilled &&
         !prefilled_placeholder_username) {
       // Username is filled with content that was not on a list of known
       // placeholder texts (e.g. "username or email") nor there is server-side
@@ -1605,8 +1606,10 @@ bool PasswordAutofillAgent::FillUserNameAndPassword(
 
   // Input matches the username, fill in required values.
   if (!username_element.IsNull() && IsElementEditable(username_element)) {
-    if (!username.empty() && (username_element.Value().IsEmpty() ||
-                              prefilled_placeholder_username)) {
+    if (!username.empty() &&
+        (username_element.Value().IsEmpty() ||
+         username_element.GetAutofillState() != WebAutofillState::kNotFilled ||
+         prefilled_placeholder_username)) {
       AutofillField(username, username_element);
       if (prefilled_placeholder_username) {
         LogPrefilledUsernameFillOutcome(