Missing call to base's FinishedParsingChildren in datalist.

Bug: 990767
Change-Id: I7040082705506dda5acc5c27e80d8a25822b3e2e
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1738548Reviewed-by: Mason Freed <masonfreed@chromium.org>
Commit-Queue: Rune Lillesveen <futhark@chromium.org>
Cr-Commit-Position: refs/heads/master@{#684369}

third_party/blink/renderer/core/BUILD.gn

@@ -1236,6 +1236,7 @@ jumbo_source_set("unit_tests") {
     "html/forms/file_input_type_test.cc",
     "html/forms/form_controller_test.cc",
     "html/forms/form_data_test.cc",
+    "html/forms/html_data_list_element_test.cc",
     "html/forms/html_form_control_element_test.cc",
     "html/forms/html_form_element_test.cc",
     "html/forms/html_input_element_test.cc",

third_party/blink/renderer/core/html/forms/html_data_list_element.cc

@@ -58,6 +58,7 @@ void HTMLDataListElement::ChildrenChanged(const ChildrenChange& change) {
 }
 
 void HTMLDataListElement::FinishParsingChildren() {
+  HTMLElement::FinishParsingChildren();
   GetTreeScope().GetIdTargetObserverRegistry().NotifyObservers(
       GetIdAttribute());
 }

third_party/blink/renderer/core/html/forms/html_data_list_element_test.cc

+// Copyright 2019 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 "third_party/blink/renderer/core/html/forms/html_data_list_element.h"
+#include "testing/gtest/include/gtest/gtest.h"
+#include "third_party/blink/renderer/core/dom/document.h"
+#include "third_party/blink/renderer/core/testing/sim/sim_request.h"
+#include "third_party/blink/renderer/core/testing/sim/sim_test.h"
+
+namespace blink {
+
+class HTMLDataListElementTest : public SimTest {};
+
+TEST_F(HTMLDataListElementTest, FinishedParsingChildren) {
+  SimRequest main_resource("https://example.com/", "text/html");
+
+  LoadURL("https://example.com/");
+  main_resource.Complete("<datalist id=list></datalist>");
+
+  auto* data_list = GetDocument().getElementById("list");
+  ASSERT_TRUE(data_list);
+  EXPECT_TRUE(data_list->IsFinishedParsingChildren());
+}
+
+}  // namespace blink