Remove willRequestResource callback, it is unused outside of tests.

Source/core/loader/FrameFetchContext.cpp

 /*
  * Copyright (C) 2013 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 283 matching lines @@
 
 bool FrameFetchContext::shouldLoadNewResource(Resource::Type type) const
 {
     if (!m_documentLoader)
         return true;
     if (type == Resource::MainResource)
         return m_documentLoader == frame()->loader().provisionalDocumentLoader();
     return m_documentLoader == frame()->loader().documentLoader();
 }
 
-void FrameFetchContext::dispatchWillRequestResource(FetchRequest* request)
-{
-    frame()->loader().client()->dispatchWillRequestResource(request);
-}
-
 void FrameFetchContext::willStartLoadingResource(ResourceRequest& request)
 {
     if (m_documentLoader)
         m_documentLoader->applicationCacheHost()->willStartLoadingResource(request);
 }
 
 void FrameFetchContext::didLoadResource()
 {
     frame()->loader().checkCompleted();
 }
@@ skipping 373 matching lines @@
 
 
 DEFINE_TRACE(FrameFetchContext)
 {
     visitor->trace(m_document);
     visitor->trace(m_documentLoader);
     FetchContext::trace(visitor);
 }
 
 } // namespace blink