Plumb the DragOperation through all the layers between the platform DnD code ...

chrome/common/webkit_param_traits.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 file contains ParamTraits templates to support serialization of WebKit
 // data types over IPC.
 //
 // NOTE: IT IS IMPORTANT THAT ONLY POD (plain old data) TYPES ARE SERIALIZED.
 //
 // There are several reasons for this restrictions:
 //
 //   o  We don't want inclusion of this file to imply linking to WebKit code.
 //
 //   o  Many WebKit structures are not thread-safe.  WebString, for example,
 //      contains a reference counted buffer, which does not use thread-safe
 //      reference counting.  If we allowed serializing WebString, then we may run
 //      the risk of introducing subtle thread-safety bugs if people passed a
 //      WebString across threads via PostTask(NewRunnableMethod(...)).
 //
 //   o  The WebKit API has redundant types for strings, and we should avoid using
 //      those beyond code that interfaces with the WebKit API.
 
 #ifndef CHROME_COMMON_WEBKIT_PARAM_TRAITS_H_
 #define CHROME_COMMON_WEBKIT_PARAM_TRAITS_H_
 
 #include "ipc/ipc_message_utils.h"
 #include "webkit/api/public/WebCache.h"
 #include "webkit/api/public/WebCompositionCommand.h"
 #include "webkit/api/public/WebConsoleMessage.h"
+#include "webkit/api/public/WebDragOperation.h"
 #include "webkit/api/public/WebFindOptions.h"
 #include "webkit/api/public/WebInputEvent.h"
 #include "webkit/api/public/WebScreenInfo.h"
 #include "webkit/api/public/WebTextDirection.h"
 
 namespace IPC {
 
 template <>
 struct ParamTraits<WebKit::WebRect> {
   typedef WebKit::WebRect param_type;
@@ skipping 255 matching lines @@
     if (!ReadParam(m, iter, &value))
       return false;
     *r = static_cast<param_type>(value);
     return true;
   }
   static void Log(const param_type& p, std::wstring* l) {
     LogParam(static_cast<int>(p), l);
   }
 };
 
+template <>
+  struct ParamTraits<WebKit::WebDragOperation> {
+  typedef WebKit::WebDragOperation param_type;
+  static void Write(Message* m, const param_type& p) {
+    m->WriteInt(p);
+  }
+  static bool Read(const Message* m, void** iter, param_type* r) {
+    int temp;
+    bool res = m->ReadInt(iter, &temp);
+    *r = static_cast<param_type>(temp);
+    return res;
+  }
+  static void Log(const param_type& p, std::wstring* l) {
+    l->append(StringPrintf(L"%d", p));
+  }
+};
+
 }  // namespace IPC
 
 #endif  // CHROME_COMMON_WEBKIT_PARAM_TRAITS_H_