Fix an ODR violation for ModalDialogDelegate found by ASan

ui/views/widget/widget_unittest.cc

 // Copyright (c) 2012 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 <algorithm>
 #include <memory>
 #include <set>
 
 #include "base/bind.h"
 #include "base/environment.h"
@@ skipping 3618 matching lines @@
   // Moving the child to a different widget should call the removals observer.
   WidgetAutoclosePtr widget2(CreateTopLevelPlatformWidget());
   widget2->client_view()->AddChildView(child);
   EXPECT_TRUE(removals_observer.DidRemoveView(child));
 
   widget->RemoveRemovalsObserver(&removals_observer);
 }
 
 #if defined(OS_WIN)
 
+namespace {
+
 // Provides functionality to create a window modal dialog.
 class ModalDialogDelegate : public DialogDelegateView {
 public:
   explicit ModalDialogDelegate(ui::ModalType type) : type_(type) {}
   ~ModalDialogDelegate() override {}
 
   // WidgetDelegate overrides.
   ui::ModalType GetModalType() const override { return type_; }
 
 private:
   const ui::ModalType type_;
 
   DISALLOW_COPY_AND_ASSIGN(ModalDialogDelegate);
 };
 
+}  // namespace
+
 // Tests the case where an intervening owner popup window is destroyed out from
 // under the currently active modal top-level window. In this instance, the
 // remaining top-level windows should be re-enabled.
 TEST_F(WidgetTest, WindowModalOwnerDestroyedEnabledTest) {
   // Modality etc. are controlled by mus.
   if (IsMus())
     return;
   // top_level_widget owns owner_dialog_widget which owns owned_dialog_widget.
   Widget top_level_widget;
   Widget owner_dialog_widget;
@@ skipping 135 matching lines @@
                              CreateParams(Widget::InitParams::TYPE_WINDOW),
                              Widget::InitParams::TRANSLUCENT_WINDOW);
   EXPECT_EQ(IsNativeWindowTransparent(widget.GetNativeWindow()),
             widget.ShouldWindowContentsBeTransparent());
 }
 
 #endif  // !defined(OS_CHROMEOS)
 
 }  // namespace test
 }  // namespace views