Remove ResourceFetcher's access to a real FetchContext at frame detach time

Source/core/fetch/FetchContext.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 16 matching lines @@
  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
  * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  */
 
 #include "config.h"
 #include "core/fetch/FetchContext.h"
 
 
 namespace blink {
 
+FetchContext& FetchContext::nullInstance()
+{
+    DEFINE_STATIC_LOCAL(OwnPtrWillBePersistent<FetchContext>, instance, (adoptPtrWillBeNoop(new FetchContext)));
+    return *instance;
+}
+
 void FetchContext::dispatchDidChangeResourcePriority(unsigned long, ResourceLoadPriority, int)
 {
 }
 
 void FetchContext::addAdditionalRequestHeaders(ResourceRequest&, FetchResourceType)
 {
 }
 
 void FetchContext::setFirstPartyForCookies(ResourceRequest&)
 {
@@ skipping 71 matching lines @@
 
 void FetchContext::addClientHintsIfNecessary(FetchRequest&)
 {
 }
 
 void FetchContext::addCSPHeaderIfNecessary(Resource::Type, FetchRequest&)
 {
 }
 
 } // namespace blink