[breadcrumb] Add breadcrumb unittest

Add unittest fixtures (18 in all) to cover the breadcrumbs public API.

Note that Polymer3 does not work in files app unittest harness, so the
<cr-action-menu> aspects of breadcrumb can only be partly tested here,
see [1]. Keyboard Enter and Space, and <cr-action-menu> drop-down menu
open/close behavior etc will need integration tests.

[1] The <cr-action-menu> fails on a "Polymer is not defined" exception
at unittest start-up and its JS code is non-functional as a result.

Bug: 1061388
Change-Id: Ie2d03cb16dbcde421131c933c92a3a0e4a1e7f1d
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2143024Reviewed-by: Noel Gordon <noel@chromium.org>
Reviewed-by: Alex Danilo <adanilo@chromium.org>
Commit-Queue: Noel Gordon <noel@chromium.org>
Cr-Commit-Position: refs/heads/master@{#757763}

chrome/browser/chromeos/file_manager/file_manager_jstest.cc

@@ -27,6 +27,10 @@ IN_PROC_BROWSER_TEST_F(FileManagerJsTest, ActionsModelTest) {
   RunTestURL("foreground/js/actions_model_unittest_gen.html");
 }
 
+IN_PROC_BROWSER_TEST_F(FileManagerJsTest, Breadcrumb) {
+  RunTestURL("foreground/js/ui/breadcrumb_unittest_gen.html");
+}
+
 IN_PROC_BROWSER_TEST_F(FileManagerJsTest, NavigationListModelTest) {
   RunTestURL("foreground/js/navigation_list_model_unittest_gen.html");
 }

ui/file_manager/file_manager/foreground/js/ui/BUILD.gn

@@ -123,9 +123,14 @@ js_library("banners") {
 }
 
 js_library("breadcrumb") {
+  deps = [ "//ui/webui/resources/cr_elements/cr_action_menu:cr_action_menu" ]
+}
+
+js_unittest("breadcrumb_unittest") {
   deps = [
-    "//ui/webui/resources/cr_elements/cr_action_menu:cr_action_menu",
+    ":breadcrumb",
     "//ui/webui/resources/js:assert",
+    "//ui/webui/resources/js:webui_resource_test",
   ]
 }
 
@@ -506,6 +511,7 @@ js_library("suggest_apps_dialog") {
 js_test_gen_html("js_test_gen_html") {
   deps = [
     ":actions_submenu_unittest",
+    ":breadcrumb_unittest",
     ":directory_tree_unittest",
     ":file_list_selection_model_unittest",
     ":file_manager_dialog_base_unittest",