aura: Gesture event plumbing (skeleton).

ui/aura/event.h

 // Copyright (c) 2011 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_AURA_EVENT_H_
 #define UI_AURA_EVENT_H_
 #pragma once
 
 #include "base/basictypes.h"
 #include "base/event_types.h"
@@ skipping 200 matching lines @@
   const ui::OSExchangeData& data_;
 
   // Bitmask of supported ui::DragDropTypes::DragOperation by the source.
   int source_operations_;
 
   DISALLOW_COPY_AND_ASSIGN(DropTargetEvent);
 };
 
 class AURA_EXPORT ScrollEvent : public MouseEvent {
  public:
-  ScrollEvent(const base::NativeEvent& native_event);
+  explicit ScrollEvent(const base::NativeEvent& native_event);
   ScrollEvent(const ScrollEvent& model,
               Window* source,
               Window* target,
               ui::EventType type,
               int flags)
       : MouseEvent(model, source, target, type, flags),
         x_offset_(model.x_offset_),
         y_offset_(model.y_offset_) {
   }
 
   float x_offset() const { return x_offset_; }
   float y_offset() const { return y_offset_; }
 
  private:
   float x_offset_;
   float y_offset_;
 
   DISALLOW_COPY_AND_ASSIGN(ScrollEvent);
 };
 
+class AURA_EXPORT GestureEvent : public LocatedEvent {
+};
+
 }  // namespace aura
 
 #endif  // UI_AURA_EVENT_H_