Implement ui::ClipboardMus.

ui/views/mus/clipboard_unittest.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 "ui/views/mus/clipboard_mus.h"
+
+#include "base/message_loop/message_loop.h"
+#include "testing/gtest/include/gtest/gtest.h"
+#include "ui/events/platform/platform_event_source.h"
+#include "ui/views/mus/window_manager_connection.h"
+#include "ui/views/test/scoped_views_test_helper.h"
+
+namespace ui {
+
+struct PlatformClipboardTraits {
+  static std::unique_ptr<PlatformEventSource> GetEventSource() {
+    return std::unique_ptr<PlatformEventSource>();

[dcheng, 2016/06/04 06:14:00]

Nit: nullptr

+  }
+
+  static Clipboard* Create() {
+    EXPECT_FALSE(test_helper.get());

[dcheng, 2016/06/04 06:14:01]

Nit: EXPECT_FALSE(test_helper)

+
+    // We need to set up enough of views so that it reaches out to mus for a
+    // window manager connection.
+    test_helper.reset(new views::ScopedViewsTestHelper);
+
+    // If we don't have a window manager connection, we will get the default
+    // platform clipboard instead.
+    EXPECT_TRUE(views::WindowManagerConnection::Exists());
+
+    return Clipboard::GetForCurrentThread();
+  }
+
+  static bool IsMusTest() { return true; }
+
+  static void Destroy(Clipboard* clipboard) {
+    ASSERT_EQ(Clipboard::GetForCurrentThread(), clipboard);
+    Clipboard::DestroyClipboardForCurrentThread();
+
+    test_helper.reset();
+  }
+
+  static std::unique_ptr<views::ScopedViewsTestHelper> test_helper;
+};
+
+std::unique_ptr<views::ScopedViewsTestHelper>
+    PlatformClipboardTraits::test_helper;

[dcheng, 2016/06/04 06:14:00]

I don't think we allow globals of non-POD type.

[Elliot Glaysher, 2016/06/06 20:10:12]

In chrome code. This is in a unit test.

I also don't see a way to avoid this, unless you're talking about linkage, in
which case I put this in an anonymous namespace.

[dcheng, 2016/06/07 05:39:00]

I don't think the style guide distinguishes between test code and not-test code:
https://google.github.io/styleguide/cppguide.html#Static_and_Global_Variables

[Elliot Glaysher, 2016/06/07 17:16:19]

Replaced static with a forwarding subclass of ui::Clipboard which also owns the
ScoepdVeiwsTestHelper.

+
+typedef PlatformClipboardTraits TypesToTest;

[dcheng, 2016/06/04 06:14:00]

Nit: using (I guess this is copying the pattern in the existing test
instantiations, but we may as well use the recommended way in new code)

+
+}  // namespace ui
+
+#include "ui/base/clipboard/clipboard_test_template.h"