Bug 1651532 - Change systemDefaultPrinter to systemDefaultPrinterName r=jwatt

The `systemDefaultPrinter` attribute in `nsIPrinterList` currently has
only one usage: to retrieve the printer's name. This patch changes the
attribute to be the name instead of the whole printer until such
funcationality is needed.

Differential Revision: https://phabricator.services.mozilla.com/D82951

widget/cocoa/nsDeviceContextSpecX.mm

@@ -47,19 +47,14 @@ static LazyLogModule sDeviceContextSpecXLog("DeviceContextSpecX");
 NS_IMPL_ISUPPORTS(nsPrinterListX, nsIPrinterList);
 
 NS_IMETHODIMP
-nsPrinterListX::GetSystemDefaultPrinter(nsIPrinter** aDefaultPrinter) {
+nsPrinterListX::GetSystemDefaultPrinterName(nsAString& aName) {
   NS_OBJC_BEGIN_TRY_ABORT_BLOCK_NSRESULT;
 
-  NS_ENSURE_ARG_POINTER(aDefaultPrinter);
-  *aDefaultPrinter = nullptr;
-
+  aName.Truncate();
   NSArray<NSString*>* printerNames = [NSPrinter printerNames];
   if ([printerNames count] > 0) {
     NSString* name = [printerNames objectAtIndex:0];
-    nsAutoString printerName;
-    nsCocoaUtils::GetStringForNSString(name, printerName);
-    *aDefaultPrinter = new nsPrinter(printerName);
-    NS_ADDREF(*aDefaultPrinter);
+    nsCocoaUtils::GetStringForNSString(name, aName);
     return NS_OK;
   }
 

widget/gtk/nsDeviceContextSpecG.cpp

@@ -372,13 +372,8 @@ nsPrinterListGTK::GetPrinters(nsTArray<RefPtr<nsIPrinter>>& aPrinters) {
 }
 
 NS_IMETHODIMP
-nsPrinterListGTK::GetSystemDefaultPrinter(nsIPrinter** aDefaultPrinter) {
-  nsAutoString printerName;
-  GlobalPrinters::GetInstance()->GetSystemDefaultPrinterName(printerName);
-
-  *aDefaultPrinter = new nsPrinter(printerName);
-  NS_ADDREF(*aDefaultPrinter);
-
+nsPrinterListGTK::GetSystemDefaultPrinterName(nsAString& aName) {
+  GlobalPrinters::GetInstance()->GetSystemDefaultPrinterName(aName);
   return NS_OK;
 }
 

widget/nsIPrinterList.idl

@@ -23,12 +23,11 @@ interface nsIPrinterList : nsISupports
                                     in nsIPrintSettings aPrintSettings);
 
   /**
-   * The system default printer. This should also be
-   * present in printers below. This is not necessarily gecko's
+   * The system default printer name. This is not necessarily gecko's
    * default printer; see nsIPrintSettingsService.lastUsedPrinterName
    * for that.
    */
-  readonly attribute nsIPrinter systemDefaultPrinter;
+  readonly attribute AString systemDefaultPrinterName;
 
   /**
    * The list of printers.

widget/nsPrintSettingsService.cpp

@@ -921,11 +921,7 @@ nsPrintSettingsService::GetLastUsedPrinterName(
 
   // There is no last printer preference, or it doesn't name a valid printer.
   // Return the system default from the printer list.
-  RefPtr<nsIPrinter> defaultPrinter;
-  printerList->GetSystemDefaultPrinter(getter_AddRefs(defaultPrinter));
-  if (defaultPrinter) {
-    defaultPrinter->GetName(aLastUsedPrinterName);
-  }
+  printerList->GetSystemDefaultPrinterName(aLastUsedPrinterName);
   return NS_OK;
 }
 

widget/windows/nsDeviceContextSpecWin.cpp

@@ -514,13 +514,8 @@ nsresult nsDeviceContextSpecWin::GetDataFromPrinter(const nsAString& aName,
 NS_IMPL_ISUPPORTS(nsPrinterListWin, nsIPrinterList)
 
 NS_IMETHODIMP
-nsPrinterListWin::GetSystemDefaultPrinter(nsIPrinter** aDefaultPrinter) {
-  NS_ENSURE_ARG_POINTER(aDefaultPrinter);
-  *aDefaultPrinter = nullptr;
-  nsAutoString printerName;
-  GlobalPrinters::GetInstance()->GetDefaultPrinterName(printerName);
-  *aDefaultPrinter = new nsPrinter(printerName);
-  NS_ADDREF(*aDefaultPrinter);
+nsPrinterListWin::GetSystemDefaultPrinterName(nsAString& aName) {
+  GlobalPrinters::GetInstance()->GetDefaultPrinterName(aName);
   return NS_OK;
 }
 

widget/windows/nsPrintDialogUtil.cpp

@@ -136,14 +136,11 @@ static nsReturnRef<nsHGLOBAL> CreateGlobalDevModeAndInit(
 //------------------------------------------------------------------
 // helper
 static void GetDefaultPrinterNameFromGlobalPrinters(nsAString& aPrinterName) {
+  aPrinterName.Truncate();
   nsCOMPtr<nsIPrinterList> printerList =
       do_GetService("@mozilla.org/gfx/printerlist;1");
   if (printerList) {
-    nsIPrinter* printer = nullptr;
-    printerList->GetSystemDefaultPrinter(&printer);
-    if (printer) {
-      printer->GetName(aPrinterName);
-    }
+    printerList->GetSystemDefaultPrinterName(aPrinterName);
   }
 }