Add a TestBrowserDialog helper class for testing browser dialogs in a consistent way.

chrome/test/BUILD.gn

 # Copyright 2014 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("//build/config/chrome_build.gni")
 import("//build/config/compiler/compiler.gni")
 import("//build/config/crypto.gni")
 import("//build/config/features.gni")
 import("//build/config/ui.gni")
 import("//chrome/common/features.gni")
@@ skipping 1756 matching lines @@
       "../browser/ui/search/new_tab_page_interceptor_browsertest.cc",
       "../browser/ui/search_engines/search_engine_tab_helper_browsertest.cc",
       "../browser/ui/settings_window_manager_browsertest.cc",
       "../browser/ui/startup/startup_browser_creator_browsertest.cc",
       "../browser/ui/startup/startup_browser_creator_corrupt_profiles_browsertest_win.cc",
       "../browser/ui/startup/startup_browser_creator_triggered_reset_browsertest_win.cc",
       "../browser/ui/sync/one_click_signin_links_delegate_impl_browsertest.cc",
       "../browser/ui/sync/profile_signin_confirmation_helper_browsertest.cc",
       "../browser/ui/tab_modal_confirm_dialog_browsertest.cc",
       "../browser/ui/tab_modal_confirm_dialog_browsertest.h",
+      "../browser/ui/test/browser_dialog_browsertest.cc",
+      "../browser/ui/test/test_browser_dialog.cc",
+      "../browser/ui/test/test_browser_dialog.h",
       "../browser/ui/toolbar/browser_actions_bar_browsertest.cc",
       "../browser/ui/toolbar/browser_actions_bar_browsertest.h",
       "../browser/ui/toolbar/component_toolbar_actions_browsertest.cc",
       "../browser/ui/toolbar/mock_component_toolbar_actions_factory.cc",
       "../browser/ui/toolbar/mock_component_toolbar_actions_factory.h",
       "../browser/ui/website_settings/mock_permission_prompt.cc",
       "../browser/ui/website_settings/mock_permission_prompt.h",
       "../browser/ui/website_settings/mock_permission_prompt_factory.cc",
       "../browser/ui/website_settings/mock_permission_prompt_factory.h",
       "../browser/ui/website_settings/permission_bubble_browser_test_util.cc",
@@ skipping 3331 matching lines @@
 }
 
 if (is_win) {
   loadable_module("conflicts_dll") {
     testonly = true
     sources = [
       "conflicts/conflicts_dll.cc",
     ]
   }
 }