Check validity of the parameters in OnGeneratedPasswordAccepted.

Bug: 1027152
Change-Id: I1005d4982f16e0413e646261df6ea49c39285ad9
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1929243Reviewed-by: Jan Wilken Dörrie <jdoerrie@chromium.org>
Commit-Queue: Vasilii Sukhanov <vasilii@chromium.org>
Cr-Commit-Position: refs/heads/master@{#717740}

components/password_manager/core/browser/password_form_manager.cc

@@ -722,7 +722,9 @@ void PasswordFormManager::OnGeneratedPasswordAccepted(
                            return generation_element_id ==
                                   field_data.unique_renderer_id;
                          });
-  DCHECK(it != form_data.fields.end());
+  // The parameters are coming from the renderer and can't be trusted.
+  if (it == form_data.fields.end())
+    return;
   it->value = password;
   std::unique_ptr<PasswordForm> parsed_form =
       ParseFormAndMakeLogging(form_data, FormDataParser::Mode::kSaving);

components/password_manager/core/browser/password_form_manager_unittest.cc

@@ -2496,6 +2496,14 @@ TEST_F(PasswordFormManagerTestWithMockedSaver, PasswordNoLongerGenerated) {
   CheckPasswordGenerationUKM(test_ukm_recorder, expected_metrics);
 }
 
+TEST_F(PasswordFormManagerTestWithMockedSaver,
+       OnGeneratedPasswordAccepted_InvalidField) {
+  FormData form_data = observed_form_only_password_fields_;
+  // A call with a non-existent password field should not crash.
+  form_manager_->OnGeneratedPasswordAccepted(std::move(form_data), 12345,
+                                             ASCIIToUTF16("new_password"));
+}
+
 TEST_F(PasswordFormManagerTestWithMockedSaver, SaveHttpAuthNoHttpAuthStored) {
   TestMockTimeTaskRunner::ScopedContext scoped_context(task_runner_.get());
   for (bool html_credentials_saved : {false, true}) {