Make using WebContentsUserData simpler.

chrome/browser/printing/print_preview_message_handler.h

 // Copyright (c) 2012 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 CHROME_BROWSER_PRINTING_PRINT_PREVIEW_MESSAGE_HANDLER_H_
 #define CHROME_BROWSER_PRINTING_PRINT_PREVIEW_MESSAGE_HANDLER_H_
 
 #include "base/compiler_specific.h"
 #include "chrome/browser/common/web_contents_user_data.h"
 #include "content/public/browser/web_contents_observer.h"
@@ skipping 17 matching lines @@
     : public content::WebContentsObserver,
       public WebContentsUserData<PrintPreviewMessageHandler> {
  public:
   virtual ~PrintPreviewMessageHandler();
 
   // content::WebContentsObserver implementation.
   virtual bool OnMessageReceived(const IPC::Message& message) OVERRIDE;
 
  private:
   explicit PrintPreviewMessageHandler(content::WebContents* web_contents);
-  static int kUserDataKey;
   friend class WebContentsUserData<PrintPreviewMessageHandler>;
 
   // Gets the print preview tab associated with the WebContents being observed.
   TabContents* GetPrintPreviewTab();
 
   // Gets the PrintPreviewUI associated with the WebContents being observed.
   PrintPreviewUI* GetPrintPreviewUI();
 
   // Message handlers.
   void OnRequestPrintPreview(bool source_is_modifiable, bool webnode_only);
@@ skipping 10 matching lines @@
   void OnPrintPreviewCancelled(int document_cookie);
   void OnInvalidPrinterSettings(int document_cookie);
   void OnPrintPreviewScalingDisabled();
 
   DISALLOW_COPY_AND_ASSIGN(PrintPreviewMessageHandler);
 };
 
 }  // namespace printing
 
 #endif  // CHROME_BROWSER_PRINTING_PRINT_PREVIEW_MESSAGE_HANDLER_H_