Provide an override for Webview drop effect....

webkit/glue/webview.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.
 
 #ifndef WEBKIT_GLUE_WEBVIEW_H_
 #define WEBKIT_GLUE_WEBVIEW_H_
 
 #include <string>
 #include <vector>
 
@@ skipping 176 matching lines @@
 
   // Notifies the webview that a drag and drop operation is in progress, with
   // dropable items over the view.
   virtual void DragSourceMovedTo(
       const WebKit::WebPoint& client_point,
       const WebKit::WebPoint& screen_point) = 0;
 
   // Notfies the webview that the system drag and drop operation has ended.
   virtual void DragSourceSystemDragEnded() = 0;
 
-  // Callback methods when a drag and drop operation is trying to drop
-  // something on the renderer.
+  // Callback methods when a drag and drop operation is trying to drop data
+  // on this webview.
   virtual bool DragTargetDragEnter(
       const WebKit::WebDragData& drag_data, int identity,
       const WebKit::WebPoint& client_point,
       const WebKit::WebPoint& screen_point) = 0;
   virtual bool DragTargetDragOver(
       const WebKit::WebPoint& client_point,
       const WebKit::WebPoint& screen_point) = 0;
   virtual void DragTargetDragLeave() = 0;
   virtual void DragTargetDrop(
       const WebKit::WebPoint& client_point,
       const WebKit::WebPoint& screen_point) = 0;
+
+  // Helper method for drag and drop target operations: return the drag data
+  // identity.
   virtual int32 GetDragIdentity() = 0;
 
+  // Helper method for drag and drop target operations: override the default
+  // drop effect with either a "copy" (accept true) or "none" (accept false)
+  // effect.  Return true on success.
+  virtual bool SetDropEffect(bool accept) = 0;
+
   // Notifies the webview that autofill suggestions are available for a node.
   virtual void AutofillSuggestionsForNode(
       int64 node_id,
       const std::vector<std::wstring>& suggestions,
       int default_suggestion_index) = 0;
 
   // Hides the autofill popup if any are showing.
   virtual void HideAutofillPopup() = 0;
 
   // Returns development tools agent instance belonging to this view.
   virtual WebDevToolsAgent* GetWebDevToolsAgent() = 0;
 
  private:
   DISALLOW_COPY_AND_ASSIGN(WebView);
 };
 
 #endif  // WEBKIT_GLUE_WEBVIEW_H_