Web UI Polymer 3: Port CrContainerShadowBehavior test

Autogenerating Polymer 3 version of CrContainerShadowBehavior test,
since the behavior is now autogenerated (see
https://crrev.com/c/1779435)

Bug: 965770
Change-Id: Ieb01a2e8c7fa31f5b56028e61c428ab0d012dd41
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1789749Reviewed-by: Esmael Elmoslimany <aee@chromium.org>
Commit-Queue: Rebekah Potter <rbpotter@chromium.org>
Cr-Commit-Position: refs/heads/master@{#694899}

chrome/test/data/webui/BUILD.gn

@@ -163,6 +163,7 @@ js2gtest("browser_tests_js_webui") {
   ]
   data = [
     "$root_gen_dir/chrome/test/data/webui/cr_elements/cr_button_tests.m.js",
+    "$root_gen_dir/chrome/test/data/webui/cr_elements/cr_container_shadow_behavior_test.m.js",
     "$root_gen_dir/chrome/test/data/webui/cr_elements/cr_dialog_test.m.js",
     "$root_gen_dir/chrome/test/data/webui/cr_elements/cr_drawer_tests.m.js",
     "$root_gen_dir/chrome/test/data/webui/cr_elements/cr_expand_button_tests.m.js",

chrome/test/data/webui/cr_elements/BUILD.gn

@@ -8,6 +8,7 @@ js_modulizer("modulize") {
   input_files = [
     "cr_button_tests.js",
     "cr_checkbox_test.js",
+    "cr_container_shadow_behavior_test.js",
     "cr_dialog_test.js",
     "cr_drawer_tests.js",
     "cr_expand_button_tests.js",

chrome/test/data/webui/cr_elements/cr_container_shadow_behavior_test.js

@@ -2,6 +2,11 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
+// clang-format off
+// #import {CrContainerShadowBehavior} from 'chrome://resources/cr_elements/cr_container_shadow_behavior.m.js';
+// #import {Polymer, html} from 'chrome://resources/polymer/v3_0/polymer/polymer_bundled.min.js';
+// clang-format on
+
 suite('CrContainerShadowBehavior', function() {
   suiteSetup(function() {
     document.body.innerHTML = `

chrome/test/data/webui/cr_elements/cr_elements_v3_browsertest.js

@@ -53,6 +53,20 @@ TEST_F('CrElementsButtonV3Test', 'All', function() {
   mocha.run();
 });
 
+// eslint-disable-next-line no-var
+var CrElementsContainerShadowBehaviorV3Test =
+    class extends CrElementsV3BrowserTest {
+  /** @override */
+  get browsePreload() {
+    return 'chrome://test?module=cr_elements/cr_container_shadow_behavior_test.m.js';
+  }
+};
+
+TEST_F('CrElementsContainerShadowBehaviorV3Test', 'All', function() {
+  mocha.run();
+});
+
+
 // eslint-disable-next-line no-var
 var CrElementsDialogV3Test = class extends CrElementsV3BrowserTest {
   /** @override */