PrintPreview: Preview generation should not block print button.

chrome/browser/printing/print_preview_tab_controller.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.
 
 // For print preview, a print preview (PP) tab is linked with the initiator tab
 // that initiated the printing operation. If the tab initiates a second
 // printing operation while the first print preview tab is still open, that PP
 // tab is focused/activated. There may be more than one PP tab open. There is a
 // 1:1 relationship between PP tabs and initiating tabs. This class manages PP
 // tabs and initiator tabs.
@@ skipping 42 matching lines @@
   TabContents* GetInitiatorTab(TabContents* preview_tab);
 
   // Notification observer implementation.
   virtual void Observe(NotificationType type,
                        const NotificationSource& source,
                        const NotificationDetails& details);
 
   // Returns true if |tab| is a print preview tab.
   static bool IsPrintPreviewTab(TabContents* tab);
 
+  // Erase the initiator tab info associated with |preview_tab|.
+  void EraseInitiatorTabInfo(TabContents* preview_tab);
+
  private:
   friend class base::RefCounted<PrintPreviewTabController>;
 
   // 1:1 relationship between initiator tab and print preview tab.
   // Key: Preview tab.
   // Value: Initiator tab.
   typedef std::map<TabContents*, TabContents*> PrintPreviewTabMap;
 
   // Creates a new print preview tab.
   TabContents* CreatePrintPreviewTab(TabContents* initiator_tab);
@@ skipping 10 matching lines @@
   // True if the controller is waiting for a new preview tab via
   // NavigationType::NEW_PAGE.
   bool waiting_for_new_preview_page_;
 
   DISALLOW_COPY_AND_ASSIGN(PrintPreviewTabController);
 };
 
 }  // namespace printing
 
 #endif  // CHROME_BROWSER_PRINTING_PRINT_PREVIEW_TAB_CONTROLLER_H_