Pass implementation object to supplemental classes by reference

Source/core/loader/PrerendererClient.cpp

 /*
  * Copyright (C) 2012 Google Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are
  * met:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
  *     * Redistributions in binary form must reproduce the above
@@ skipping 31 matching lines @@
     return "PrerendererClient";
 }
 
 // static
 PrerendererClient* PrerendererClient::from(Page* page)
 {
     PrerendererClient* supplement = static_cast<PrerendererClient*>(Supplement<Page>::from(page, supplementName()));
     return supplement;
 }
 
-void providePrerendererClientTo(Page* page, PrerendererClient* client)
+void providePrerendererClientTo(Page& page, PrerendererClient* client)
 {
     PrerendererClient::provideTo(page, PrerendererClient::supplementName(), adoptPtr(client));
 }
 
 }