Make the cancelling of drag and drop match Safari for Windows.

chrome/common/render_messages_internal.h

 // Copyright (c) 2009 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.
 
 // This header is meant to be included in multiple passes, hence no traditional
 // header guard.
 // See ipc_message_macros.h for explanation of the macros and passes.
 
 #include <string>
 #include <vector>
@@ skipping 292 matching lines @@
                       gfx::Point /* screen_pt */)
   IPC_MESSAGE_ROUTED0(ViewMsg_DragTargetDragLeave)
   IPC_MESSAGE_ROUTED2(ViewMsg_DragTargetDrop,
                       gfx::Point /* client_pt */,
                       gfx::Point /* screen_pt */)
 
   IPC_MESSAGE_ROUTED1(ViewMsg_UploadFile, ViewMsg_UploadFile_Params)
 
   // Notifies the renderer of updates in mouse position of an in-progress
   // drag.  if |ended| is true, then the user has ended the drag operation.
-  IPC_MESSAGE_ROUTED3(ViewMsg_DragSourceEndedOrMoved,
+  IPC_MESSAGE_ROUTED4(ViewMsg_DragSourceEndedOrMoved,
                       gfx::Point /* client_pt */,
                       gfx::Point /* screen_pt */,
-                      bool /* ended */)
+                      bool /* ended */,
+                      bool /* cancelled */)
 
   // Notifies the renderer that the system DoDragDrop call has ended.
   IPC_MESSAGE_ROUTED0(ViewMsg_DragSourceSystemDragEnded)
 
   // Used to tell a render view whether it should expose various bindings
   // that allow JS content extended privileges.  See BindingsPolicy for valid
   // flag values.
   IPC_MESSAGE_ROUTED1(ViewMsg_AllowBindings,
                       int /* enabled_bindings_flags */)
 
@@ skipping 1136 matching lines @@
   // web resource.  |error_message| is a user-readable explanation of what
   // went wrong.
   IPC_MESSAGE_CONTROL1(UtilityHostMsg_UnpackWebResource_Failed,
                        std::string /* error_message, if any */)
 
   // Sent by the renderer process to acknowledge receipt of a
   // ViewMsg_CSSInsertRequest message and css has been inserted into the frame.
   IPC_MESSAGE_ROUTED0(ViewHostMsg_OnCSSInserted)
 
 IPC_END_MESSAGES(ViewHost)