Check the nullable Document::settings() before accessing.

Source/core/loader/LinkLoader.cpp

 /*
  * Copyright (C) 2011 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 114 matching lines @@
                 document.addConsoleMessage(ConsoleMessage::create(OtherMessageSource, DebugMessageLevel, String("DNS prefetch triggered for " + href.host())));
             prefetchDNS(href.host());
         }
     }
 }
 
 static void preconnectIfNeeded(const LinkRelAttribute& relAttribute, const KURL& href, Document& document)
 {
     if (relAttribute.isPreconnect() && href.isValid()) {
         ASSERT(RuntimeEnabledFeatures::linkPreconnectEnabled());
-        if (document.settings()->logDnsPrefetchAndPreconnect())
+        Settings* settings = document.settings();
+        if (settings && settings->logDnsPrefetchAndPreconnect())
             document.addConsoleMessage(ConsoleMessage::create(OtherMessageSource, DebugMessageLevel, String("Preconnect triggered for " + href.host())));
         preconnect(href);
     }
 }
 
 // TODO(yoav): Replace Resource:Type here with some way that conveys priority but not context.
 static bool getTypeFromAsAttribute(const String& as, Resource::Type& type)
 {
     if (as.isEmpty())
         return false;
@@ skipping 10 matching lines @@
         if (!href.isValid() || href.isEmpty()) {
             document.addConsoleMessage(ConsoleMessage::create(OtherMessageSource, WarningMessageLevel, String("<link rel=preload> has an invalid `href` value")));
             return;
         }
         Resource::Type type;
         if (!getTypeFromAsAttribute(as, type)) {
             document.addConsoleMessage(ConsoleMessage::create(OtherMessageSource, WarningMessageLevel, String("<link rel=preload> must have a valid `as` value")));
             return;
         }
         FetchRequest linkRequest(ResourceRequest(document.completeURL(href)), FetchInitiatorTypeNames::link);
-        if (document.settings()->logPreload())
+        Settings* settings = document.settings();
+        if (settings && settings->logPreload())
             document.addConsoleMessage(ConsoleMessage::create(OtherMessageSource, DebugMessageLevel, String("Preload triggered for " + href.host() + href.path())));
         setResource(document.fetcher()->fetchLinkPreloadResource(type, linkRequest));
     }
 }
 
 bool LinkLoader::loadLinkFromHeader(const String& headerValue, Document* document)
 {
     if (!document)
         return false;
     LinkHeaderSet headerSet(headerValue);
@@ skipping 57 matching lines @@
         m_prerender.clear();
     }
 }
 
 DEFINE_TRACE(LinkLoader)
 {
     visitor->trace(m_prerender);
 }
 
 }