Print Preview: Display a throbber when the user requests the system print

chrome/browser/printing/print_view_manager.h

Index: chrome/browser/printing/print_view_manager.h
diff --git a/chrome/browser/printing/print_view_manager.h b/chrome/browser/printing/print_view_manager.h
index 308400dba0323195c7feab8b33675c8640ceaa6a..7dbabf0a853d2002f27caf9844ab3bf4a7482123 100644
--- a/chrome/browser/printing/print_view_manager.h
+++ b/chrome/browser/printing/print_view_manager.h
@@ -22,6 +22,7 @@ namespace printing {
 class JobEventDetails;
 class PrintJob;
 class PrintJobWorkerOwner;
+class PrintViewManagerDelegate;
 
 // Manages the print commands in relation to a TabContents. TabContents
 // delegates a few printing related commands to this instance.
@@ -38,8 +39,10 @@ class PrintViewManager : public NotificationObserver,
 
   // Prints the current document immediately. Since the rendering is
   // asynchronous, the actual printing will not be completed on the return of
-  // this function. Returns false if printing is impossible at the moment.
-  bool PrintNow();
+  // this function. |delegate| is optional and may be used to be notified when
+  // the print dialog is shown. Returns false if printing is impossible at the
+  // moment.
+  bool PrintNow(PrintViewManagerDelegate* delegate);

[Lei Zhang, 2011/06/21 01:54:46]

Since we expect |delegate| to be NULL most of the time, can we leave PrintNow()
as it was before and add PrintNowWithDelegate(PVMD* delegate)?

[James Hawkins, 2011/06/22 23:47:24]

I'd rather not, as that complicates the API unnecessarily by adding another
method.

 
   // Initiate print preview of the current document by first notifying the
   // renderer. Since this happens asynchronous, the print preview tab creation
@@ -71,6 +74,7 @@ class PrintViewManager : public NotificationObserver,
  private:
   // IPC Message handlers.
   void OnDidGetPrintedPagesCount(int cookie, int number_pages);
+  void OnDidShowPrintDialog();
   void OnDidPrintPage(const PrintHostMsg_DidPrintPage_Params& params);
   void OnPrintingFailed(int cookie);
 
@@ -150,6 +154,9 @@ class PrintViewManager : public NotificationObserver,
   bool is_title_overridden_;
   string16 overridden_title_;
 
+  // Weak pointer to a delegate that is notified when the print dialog is shown.
+  PrintViewManagerDelegate* delegate_;
+
   DISALLOW_COPY_AND_ASSIGN(PrintViewManager);
 };