mash: Fix DCHECK when clicking on window close box

ui/events/event.h

 // 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.
 
 #ifndef UI_EVENTS_EVENT_H_
 #define UI_EVENTS_EVENT_H_
 
 #include <stdint.h>
 #include "base/compiler_specific.h"
 #include "base/event_types.h"
@@ skipping 719 matching lines @@
   bool should_remove_native_touch_id_mapping_;
 
   // Structure for holding pointer details for implementing PointerEvents API.
   PointerDetails pointer_details_;
 };
 
 class EVENTS_EXPORT PointerEvent : public LocatedEvent {
  public:
   static const int32_t kMousePointerId;
 
+  // Returns true if a PointerEvent can be constructed from the given mouse or
+  // touch event. For example, PointerEvent does not support ET_MOUSEWHEEL or
+  // ET_MOUSE_CAPTURE_CHANGED.
+  static bool CanConvertFrom(const Event& event);
+
   PointerEvent(const PointerEvent& pointer_event);
   explicit PointerEvent(const MouseEvent& mouse_event);
   explicit PointerEvent(const TouchEvent& touch_event);
 
   PointerEvent(EventType type,
                EventPointerType pointer_type,
                const gfx::Point& location,
                const gfx::Point& root_location,
                int flags,
                int pointer_id,
@@ skipping 305 matching lines @@
       : LocatedEvent(type, time_stamp, flags) {}
   friend struct IPC::ParamTraits<ui::ScopedEvent>;
   friend struct IPC::ParamTraits<ui::GestureEvent>;
 
   GestureEventDetails details_;
 };
 
 }  // namespace ui
 
 #endif  // UI_EVENTS_EVENT_H_