Print preview page selection should not require a rerendering of draft pages.

chrome/browser/printing/print_preview_data_service.h

 // 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.
 
 #ifndef CHROME_BROWSER_PRINTING_PRINT_PREVIEW_DATA_SERVICE_H_
 #define CHROME_BROWSER_PRINTING_PRINT_PREVIEW_DATA_SERVICE_H_
 #pragma once
 
 #include <map>
 #include <string>
@@ skipping 22 matching lines @@
   // or |printing::COMPLETE_PREVIEW_DOCUMENT_INDEX| to represent complete
   // preview data. Use |index| to set/update a specific preview page data.
   // NOTE: PrintPreviewDataStore owns the data. Do not refcount |data| before
   // calling this function. It will be refcounted in PrintPreviewDataStore.
   void SetDataEntry(const std::string& preview_ui_addr_str, int index,
                     const RefCountedBytes* data);
 
   // Remove the corresponding PrintPreviewUI entry from the map.
   void RemoveEntry(const std::string& preview_ui_addr_str);
 
+  // Returns true if all the individual preview pages are available.
+  bool IsDraftPagesAvailable(const std::string& preview_ui_addr_str,

[vandebo (ex-Chrome), 2011/08/29 18:21:56]

This API is pretty fragile, you only get the right answer if you pass in the
correct count of draft pages.  Maybe it would be better to make more explicit
what information is available.  i.e. Make this method return the number of draft
pages stored.  Then the caller could compare that to the number it knows should
be there to come to the answer it needs.

[kmadhusu, 2011/08/30 17:27:00]

Done.

+                             int draft_page_count);
+
  private:
   friend struct DefaultSingletonTraits<PrintPreviewDataService>;
 
   // 1:1 relationship between PrintPreviewUI and data store object.
   // Key: Print preview UI address string.
   // Value: Print preview data store object.
   typedef std::map<std::string, scoped_refptr<PrintPreviewDataStore> >
       PreviewDataStoreMap;
 
   PrintPreviewDataService();
   virtual ~PrintPreviewDataService();
 
   PreviewDataStoreMap data_store_map_;
 
   DISALLOW_COPY_AND_ASSIGN(PrintPreviewDataService);
 };
 
 #endif  // CHROME_BROWSER_PRINTING_PRINT_PREVIEW_DATA_SERVICE_H_