Switch PrintViewManager, PrintPreviewMessageHandler to use WebContentsUserData.

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/tab_contents/web_contents_user_data.h"
 #include "content/public/browser/web_contents_observer.h"
 
 class PrintPreviewUI;
 class TabContents;
 struct PrintHostMsg_DidGetPreviewPageCount_Params;
 struct PrintHostMsg_DidPreviewDocument_Params;
 struct PrintHostMsg_DidPreviewPage_Params;
 
 namespace gfx {
 class Rect;
 }
 
 namespace printing {
 
 struct PageSizeMargins;
 
-// TabContents offloads print preview message handling to
-// PrintPreviewMessageHandler. This object has the same life time as the
-// TabContents that owns it.
-class PrintPreviewMessageHandler : public content::WebContentsObserver {
+// Manages the print preview handling for a WebContents.
+class PrintPreviewMessageHandler
+    : public content::WebContentsObserver,
+      public WebContentsUserData<PrintPreviewMessageHandler> {
  public:
-  explicit PrintPreviewMessageHandler(content::WebContents* web_contents);
   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();
 
-  // Helper function to return the TabContents for web_contents().
-  TabContents* tab_contents();
-
   // Gets the PrintPreviewUI associated with the WebContents being observed.
   PrintPreviewUI* GetPrintPreviewUI();
 
   // Message handlers.
   void OnRequestPrintPreview(bool source_is_modifiable, bool webnode_only);
   void OnDidGetDefaultPageLayout(
       const printing::PageSizeMargins& page_layout_in_points,
       const gfx::Rect& printable_area_in_points,
       bool has_custom_page_size_style);
   void OnDidGetPreviewPageCount(
       const PrintHostMsg_DidGetPreviewPageCount_Params& params);
   void OnDidPreviewPage(const PrintHostMsg_DidPreviewPage_Params& params);
   void OnMetafileReadyForPrinting(
       const PrintHostMsg_DidPreviewDocument_Params& params);
   void OnPrintPreviewFailed(int document_cookie);
   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_