Basic DragImage implementation....

chrome/common/render_messages_internal.h

 // Copyright (c) 2010 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 <map>
 #include <string>
@@ skipping 1426 matching lines @@
                       std::vector<webkit_glue::PasswordForm> /* forms */)
 
   // Notification that a form has been submitted.  The user hit the button.
   IPC_MESSAGE_ROUTED1(ViewHostMsg_FormFieldValuesSubmitted,
                       webkit_glue::FormFieldValues /* form */)
 
   // Used to tell the parent the user started dragging in the content area. The
   // WebDropData struct contains contextual information about the pieces of the
   // page the user dragged. The parent uses this notification to initiate a
   // drag session at the OS level.
-  IPC_MESSAGE_ROUTED2(ViewHostMsg_StartDragging,
+  IPC_MESSAGE_ROUTED4(ViewHostMsg_StartDragging,
                       WebDropData /* drop_data */,
-                      WebKit::WebDragOperationsMask /* ops_allowed */)
+                      WebKit::WebDragOperationsMask /* ops_allowed */,
+                      SkBitmap /* image */,
+                      gfx::Point /* image_offset */)
 
   // The page wants to update the mouse cursor during a drag & drop operation.
   // |is_drop_target| is true if the mouse is over a valid drop target.
   IPC_MESSAGE_ROUTED1(ViewHostMsg_UpdateDragCursor,
                       WebKit::WebDragOperation /* drag_operation */)
 
   // Tells the browser to move the focus to the next (previous if reverse is
   // true) focusable element.
   IPC_MESSAGE_ROUTED1(ViewHostMsg_TakeFocus, bool /* reverse */)
 
@@ skipping 807 matching lines @@
                        int /* render_view_id */,
                        int /* bridge_id */)
 
   // The |render_view_id| and |bridge_id| requests Geolocation service to
   // resume.
   IPC_MESSAGE_CONTROL2(ViewHostMsg_Geolocation_Resume,
                        int /* render_view_id */,
                        int /* bridge_id */)
 
 IPC_END_MESSAGES(ViewHost)