Filter out empty usernames while handling get() in the Credential Manager API.

components/password_manager/core/browser/credential_manager_pending_request_task.cc

Index: components/password_manager/core/browser/credential_manager_pending_request_task.cc
diff --git a/components/password_manager/core/browser/credential_manager_pending_request_task.cc b/components/password_manager/core/browser/credential_manager_pending_request_task.cc
index 26fb40ecd68e119ba209c1419c7bffb23f2ea8b3..dc995b0ad2a013c860242e2081edc6c6166207f9 100644
--- a/components/password_manager/core/browser/credential_manager_pending_request_task.cc
+++ b/components/password_manager/core/browser/credential_manager_pending_request_task.cc
@@ -23,18 +23,18 @@ namespace {
 // Send a UMA histogram about if |local_results| has empty or duplicate
 // usernames.
 void ReportAccountChooserMetrics(
-    const ScopedVector<autofill::PasswordForm>& local_results) {
+    const ScopedVector<autofill::PasswordForm>& local_results,
+    bool had_empty_username) {
   std::vector<base::string16> usernames;
   for (const auto& form : local_results)
     usernames.push_back(form->username_value);
   std::sort(usernames.begin(), usernames.end());
-  bool has_empty_username = !usernames.empty() && usernames[0].empty();
   bool has_duplicates =
       std::adjacent_find(usernames.begin(), usernames.end()) != usernames.end();
   metrics_util::AccountChooserUsabilityMetric metric;
-  if (has_empty_username && has_duplicates)
+  if (had_empty_username && has_duplicates)
     metric = metrics_util::ACCOUNT_CHOOSER_EMPTY_USERNAME_AND_DUPLICATES;
-  else if (has_empty_username)
+  else if (had_empty_username)
     metric = metrics_util::ACCOUNT_CHOOSER_EMPTY_USERNAME;
   else if (has_duplicates)
     metric = metrics_util::ACCOUNT_CHOOSER_DUPLICATES;
@@ -115,6 +115,14 @@ void CredentialManagerPendingRequestTask::OnGetPasswordStoreResults(
     affiliated_results.weak_clear();
   }
 
+  // Remove empty usernames from the list.
+  auto begin_empty = std::partition(local_results.begin(), local_results.end(),
+                                    [](autofill::PasswordForm* form) {
+                                      return !form->username_value.empty();
+                                    });
+  const bool has_empty_username = (begin_empty != local_results.end());
+  local_results.erase(begin_empty, local_results.end());
+
   if ((local_results.empty() && federated_results.empty())) {
     delegate_->SendCredential(send_callback_, CredentialInfo());
     return;
@@ -147,7 +155,7 @@ void CredentialManagerPendingRequestTask::OnGetPasswordStoreResults(
   std::unique_ptr<autofill::PasswordForm> potential_autosignin_form(
       new autofill::PasswordForm(*local_results[0]));
   if (!zero_click_only_)
-    ReportAccountChooserMetrics(local_results);
+    ReportAccountChooserMetrics(local_results, has_empty_username);
   if (zero_click_only_ ||
       !delegate_->client()->PromptUserToChooseCredentials(
           std::move(local_results), std::move(federated_results), origin_,