First shot at implementing drag&drop for Aura

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"
 #include "base/time.h"
 #include "ui/aura/aura_export.h"
+#include "ui/base/dragdrop/os_exchange_data.h"
 #include "ui/base/events.h"
 #include "ui/base/keycodes/keyboard_codes.h"
 #include "ui/gfx/point.h"
 
 namespace ui {
 class Transform;
 }
 
 namespace aura {
 
@@ skipping 150 matching lines @@
  private:
   ui::KeyboardCode key_code_;
   // True if this is a translated character event (vs. a raw key down). Both
   // share the same type: ui::ET_KEY_PRESSED.
   bool is_char_;
 
   uint16 character_;
   uint16 unmodified_character_;
 };
 
+class AURA_EXPORT DropTargetEvent : public LocatedEvent {
+ public:
+  DropTargetEvent(const ui::OSExchangeData& data,
+                  const gfx::Point& location,
+                  int source_operations)
+      : LocatedEvent(ui::ET_DROP_TARGET_EVENT, location, 0),
+        data_(data),
+        source_operations_(source_operations) {
+  }
+
+  const ui::OSExchangeData& data() const { return data_; }
+  int source_operations() const { return source_operations_; }
+
+ private:
+  // Data associated with the drag/drop session.
+  const ui::OSExchangeData& data_;
+
+  // Bitmask of supported ui::DragDropTypes::DragOperation by the source.
+  int source_operations_;
+
+  DISALLOW_COPY_AND_ASSIGN(DropTargetEvent);
+};
+
 }  // namespace aura
 
 #endif  // UI_AURA_EVENT_H_