Explicitly tell the preload request where to take the referrer from

third_party/WebKit/Source/core/html/parser/CSSPreloadScanner.cpp

 /*
  * Copyright (C) 2008, 2010 Apple Inc. All Rights Reserved.
  * Copyright (C) 2009 Torch Mobile, Inc. http://www.torchmobile.com/
  * Copyright (C) 2010 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:
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
@@ skipping 223 matching lines @@
 }
 
 void CSSPreloadScanner::EmitRule(const SegmentedString& source) {
   if (EqualIgnoringCase(rule_, "import")) {
     String url = ParseCSSStringOrURL(rule_value_.ToString());
     TextPosition position =
         TextPosition(source.CurrentLine(), source.CurrentColumn());
     auto request = PreloadRequest::CreateIfNeeded(
         FetchInitiatorTypeNames::css, position, url,
         *predicted_base_element_url_, Resource::kCSSStyleSheet,
-        referrer_policy_);
+        referrer_policy_, PreloadRequest::kBaseUrlIsReferrer);
     if (request) {
       // FIXME: Should this be including the charset in the preload request?
       requests_->push_back(std::move(request));
     }
     state_ = kInitial;
   } else if (EqualIgnoringCase(rule_, "charset"))
     state_ = kInitial;
   else
     state_ = kDoneParsingImportRules;
   rule_.Clear();
@@ skipping 107 matching lines @@
   resource_.Clear();
 }
 
 DEFINE_TRACE(CSSPreloaderResourceClient) {
   visitor->Trace(preloader_);
   visitor->Trace(resource_);
   StyleSheetResourceClient::Trace(visitor);
 }
 
 }  // namespace blink