--- a/toolkit/components/browser/nsIPrintingPromptService.idl
+++ b/toolkit/components/browser/nsIPrintingPromptService.idl
@@ -124,23 +124,19 @@ interface nsIPrintingPromptService : nsI
                     out nsIPrintProgressParams printProgressParams,
                     out boolean notifyOnOpen);
 
   /**
    *  Shows the print progress dialog
    *
    *  @param parent - a DOM windows the dialog will be parented to (required)
    *  @param printSettings - PrintSettings for page setup (required)
-   *  @param aObs - An observer to know if the contents of the Print Settings 
-   *                object has changed while the dialog is being shown. 
-   *                For example, some platforms may implement an "Apply" button (not required)
    */
   void showPageSetup(in mozIDOMWindowProxy parent,
-                     in nsIPrintSettings printSettings,
-                     in nsIObserver aObs);
+                     in nsIPrintSettings printSettings);
 
 };
 
 %{C++
 // {260FEDC5-524D-4aa6-9A41-E829F4C78B92}
 #define NS_PRINTINGPROMPTSERVICE_IID \
  {0x260fedc5, 0x524d, 0x4aa6, { 0x9a, 0x41, 0xe8, 0x29, 0xf4, 0xc7, 0x8b, 0x92}}
 %}

--- a/toolkit/components/printingui/ipc/nsPrintingProxy.cpp
+++ b/toolkit/components/printingui/ipc/nsPrintingProxy.cpp
@@ -177,18 +177,17 @@ nsPrintingProxy::ShowProgress(mozIDOMWin
   }
   NS_ADDREF(*printProgressParams = dialogChild);
 
   return NS_OK;
 }
 
 NS_IMETHODIMP
 nsPrintingProxy::ShowPageSetup(mozIDOMWindowProxy *parent,
-                               nsIPrintSettings *printSettings,
-                               nsIObserver *aObs)
+                               nsIPrintSettings *printSettings)
 {
   return NS_ERROR_NOT_IMPLEMENTED;
 }
 
 nsresult
 nsPrintingProxy::SavePrintSettings(nsIPrintSettings* aPS,
                                    bool aUsePrinterNamePrefix,
                                    uint32_t aFlags)

--- a/toolkit/components/printingui/nsPrintingPromptService.cpp
+++ b/toolkit/components/printingui/nsPrintingPromptService.cpp
@@ -136,18 +136,17 @@ nsPrintingPromptService::ShowProgress(
   return NS_OK;
 #else
   return NS_ERROR_NOT_IMPLEMENTED;
 #endif
 }
 
 NS_IMETHODIMP
 nsPrintingPromptService::ShowPageSetup(mozIDOMWindowProxy* parent,
-                                       nsIPrintSettings* printSettings,
-                                       nsIObserver* aObs)
+                                       nsIPrintSettings* printSettings)
 {
   NS_ENSURE_ARG(printSettings);
 
   nsCOMPtr<nsIPrintDialogService> dlgPrint(
     do_GetService(NS_PRINTDIALOGSERVICE_CONTRACTID));
   if (dlgPrint)
     return dlgPrint->ShowPageSetup(nsPIDOMWindowOuter::From(parent),
                                    printSettings);