PPAPI: Make Printing_Dev::GetDefaultPrintSettings() const.

ppapi/cpp/dev/printing_dev.h

 // 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.
 
 #ifndef PPAPI_CPP_DEV_PRINTING_DEV_H_
 #define PPAPI_CPP_DEV_PRINTING_DEV_H_
 
 #include "ppapi/c/dev/ppp_printing_dev.h"
 #include "ppapi/cpp/instance_handle.h"
 #include "ppapi/cpp/resource.h"
@@ skipping 19 matching lines @@
   virtual void PrintEnd() = 0;
   virtual bool IsPrintScalingDisabled() = 0;
 
   // PPB_Printing_Dev functions.
   // Returns true if the browser supports the required PPB_Printing_Dev
   // interface.
   static bool IsAvailable();
 
   // Outputs the default print settings for the default printer into
   // |print_settings|. Returns false on error.
-  bool GetDefaultPrintSettings(PP_PrintSettings_Dev* print_settings);
+  bool GetDefaultPrintSettings(PP_PrintSettings_Dev* print_settings) const;
 
  private:
   InstanceHandle associated_instance_;
 };
 
 }  // namespace pp
 
 #endif  // PPAPI_CPP_DEV_PRINTING_DEV_H_