Add glue for supporting custom MIME types in DataTransfer.

ui/base/clipboard/clipboard_win.cc

 // Copyright (c) 2011 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.
 
 // Many of these functions are based on those found in
 // webkit/port/platform/PasteboardWin.cpp
 
 #include "ui/base/clipboard/clipboard.h"
 
 #include <shlobj.h>
@@ skipping 526 matching lines @@
     bool has_invalid_alpha_channel = bitmap->bmiHeader.biBitCount < 32 ||
         BitmapHasInvalidPremultipliedColors(device_bitmap);
     if (has_invalid_alpha_channel) {
       MakeBitmapOpaque(device_bitmap);
     }
   }
 
   return canvas.ExtractBitmap();
 }
 
+void Clipboard::ReadCustomData(Buffer buffer,
+                               const string16& type,
+                               string16* result) const {
+  // TODO(dcheng): Implement this.
+  NOTIMPLEMENTED();
+}
+
 void Clipboard::ReadBookmark(string16* title, std::string* url) const {
   if (title)
     title->clear();
 
   if (url)
     url->clear();
 
   // Acquire the clipboard.
   ScopedClipboard clipboard;
   if (!clipboard.Acquire(GetClipboardWindow()))
@@ skipping 180 matching lines @@
     clipboard_owner_ = ::CreateWindow(L"ClipboardOwnerWindowClass",
                                       L"ClipboardOwnerWindow",
                                       0, 0, 0, 0, 0,
                                       HWND_MESSAGE,
                                       0, 0, 0);
   }
   return clipboard_owner_;
 }
 
 }  // namespace ui