Print Preview: Migrate some JS tests to use Mocha.

chrome/test/data/webui/BUILD.gn

 # Copyright 2017 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.
 
 import("//chrome/common/features.gni")
 import("//chrome/test/base/js2gtest.gni")
 
 js2gtest("interactive_ui_tests_js_webui") {
   test_type = "webui"
 
@@ skipping 133 matching lines @@
     ]
   }
   if (!enable_app_list) {
     sources -=
         [ "../../../browser/ui/webui/app_list/start_page_browsertest.js" ]
   }
   if (enable_print_preview) {
     sources += [
       "print_preview/print_preview.js",
       "print_preview/print_preview_destination_search_test.js",
+      "print_preview/print_preview_ui_browsertest.js",
     ]
   }
   deps = [
     "//chrome/browser/ui",
     "//skia",
   ]
   defines = [ "HAS_OUT_OF_PROC_TEST_RUNNER" ]
 }
 
 js2gtest("unit_tests_js") {
@@ skipping 18 matching lines @@
       "../../../browser/resources/chromeos/braille_ime/braille_ime_unittest.gtestjs",
       "../../../browser/resources/chromeos/select_to_speak/select_to_speak_unittest.gtestjs",
     ]
     extra_js_files += [
       "../../../browser/resources/chromeos/braille_ime/braille_ime.js",
       "../../../browser/resources/chromeos/select_to_speak/select_to_speak.js",
       "../../../browser/resources/chromeos/select_to_speak/test_support.js",
     ]
   }
 }