Add an identity (id) to system drag & drop.

webkit/glue/webview_impl.h

Index: webkit/glue/webview_impl.h
===================================================================
--- webkit/glue/webview_impl.h	(revision 10310)
+++ webkit/glue/webview_impl.h	(working copy)
@@ -100,6 +100,7 @@
   virtual void DragTargetDragLeave();
   virtual void DragTargetDrop(
       int client_x, int client_y, int screen_x, int screen_y);
+  virtual int32 GetDragIdentity();
   virtual void AutofillSuggestionsForNode(
       int64 node_id,
       const std::vector<std::wstring>& suggestions,
@@ -293,6 +294,14 @@
   // Represents whether or not this object should process incoming IME events.
   bool ime_accept_events_;
 
+  // True while dispatching system drag and drop events to drag/drop targets
+  // within this WebView.
+  bool drag_target_dispatch_;
+
+  // Valid when drag_target_dispatch_ is true; the identity of the drag data
+  // copied from the WebDropData object sent from the browser process.
+  int32 drag_identity_;
+
   // The autocomplete popup.  Kept around and reused every-time new suggestions
   // should be shown.
   RefPtr<WebCore::PopupContainer> autocomplete_popup_;