Context menu on views must show on mouse down for non-WIN.

ui/views/widget/widget_deletion_observer.h

+// Copyright (c) 2013 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.
+
+#ifndef UI_VIEWS_WIDGET_WIDGET_DELETION_OBSERVER_H_
+#define UI_VIEWS_WIDGET_WIDGET_DELETION_OBSERVER_H_
+
+#include "base/basictypes.h"
+#include "base/compiler_specific.h"
+#include "ui/views/widget/widget_observer.h"
+
+namespace views {
+class Widget;
+
+// A simple WidgetObserver that can be probed for the life of a widget.
+class WidgetDeletionObserver : public WidgetObserver {
+ public:
+  explicit WidgetDeletionObserver(Widget* widget);
+  virtual ~WidgetDeletionObserver();
+
+  // Returns true if the widget passed in the constructor is still alive.
+  bool IsWidgetAlive() { return widget_ != NULL; }
+
+  // Overridden from WidgetObserver.
+  virtual void OnWidgetDestroying(Widget* widget) OVERRIDE;
+
+ private:
+  void CleanupWidget();
+
+  Widget* widget_;
+
+  DISALLOW_COPY_AND_ASSIGN(WidgetDeletionObserver);
+};
+
+}  // namespace views
+
+#endif  // UI_VIEWS_WIDGET_WIDGET_DELETION_OBSERVER_H_