PPAPI: Make Printing_Dev::GetDefaultPrintSettings() const.

ppapi/cpp/dev/printing_dev.cc

 // Copyright (c) 2012 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.
 
 #include "ppapi/cpp/dev/printing_dev.h"
 
 #include "ppapi/c/dev/ppb_printing_dev.h"
 #include "ppapi/cpp/instance.h"
 #include "ppapi/cpp/instance_handle.h"
 #include "ppapi/cpp/module.h"
@@ skipping 74 matching lines @@
   Instance::RemovePerInstanceObject(associated_instance_,
                                     kPPPPrintingInterface, this);
 }
 
 // static
 bool Printing_Dev::IsAvailable() {
   return has_interface<PPB_Printing_Dev_0_6>();
 }
 
 bool Printing_Dev::GetDefaultPrintSettings(
-    PP_PrintSettings_Dev* print_settings) {
+    PP_PrintSettings_Dev* print_settings) const {
   if (!has_interface<PPB_Printing_Dev_0_6>())
     return false;
   return PP_ToBool(
       get_interface<PPB_Printing_Dev_0_6>()->GetDefaultPrintSettings(
           associated_instance_.pp_instance(), print_settings));
 }
 
 }  // namespace pp