chromeos: Makes AshTestBase/Helper target mash when appropriate

ash/mus/test/wm_test_helper.cc

 // Copyright 2016 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 "ash/mus/test/wm_test_helper.h"
 
 #include "ash/common/test/wm_shell_test_api.h"
 #include "ash/common/wm_shell.h"
 #include "ash/common/wm_window.h"
 #include "ash/mus/screen_mus.h"
@@ skipping 66 matching lines @@
   window_manager_app_.reset();
 
   base::RunLoop().RunUntilIdle();
   blocking_pool_owner_.reset();
   base::RunLoop().RunUntilIdle();
 
   ui::test::MaterialDesignControllerTestAPI::Uninitialize();
 }
 
 void WmTestHelper::Init() {
+  // General pattern is most places don't uninitialize, so we have to explicitly

[msw, 2017/02/19 21:49:20]

Can you rephrase and clarify this comment? ie. The general pattern of what? test
fixtures? WmTestBase is the only user of this class, afaict, and its TearDown
override resets the WmTestHelper instance, which already calls uninitialize, so
I'm a bit confused.

[sky, 2017/02/21 17:06:50]

I tried improving the comment. Any better?

[msw, 2017/02/22 06:25:48]

Yes, that makes more sense now.

+  // uninitialize before initializing.
+  ui::test::MaterialDesignControllerTestAPI::Uninitialize();
   ui::MaterialDesignController::Initialize();
 
   views_delegate_ = base::MakeUnique<views::TestViewsDelegate>();
 
   window_manager_app_ = base::MakeUnique<WindowManagerApplication>();
 
   message_loop_.reset(new base::MessageLoopForUI());
 
   const size_t kMaxNumberThreads = 3u;  // Matches that of content.
   const char kThreadNamePrefix[] = "MashBlockingForTesting";
@@ skipping 85 matching lines @@
   const bool is_primary =
       screen->display_list().FindDisplayById(updated_display.id()) ==
       screen->display_list().GetPrimaryDisplayIterator();
   screen->display_list().UpdateDisplay(
       updated_display, is_primary ? display::DisplayList::Type::PRIMARY
                                   : display::DisplayList::Type::NOT_PRIMARY);
 }
 
 }  // namespace mus
 }  // namespace ash