Adding Link header support for dns-prefetch

Source/core/testing/InternalSettings.h

 /*
  * Copyright (C) 2012 Google Inc. All rights reserved.
  * Copyright (C) 2013 Apple 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 105 matching lines @@
     // cannot be changed after process start. These setters should
     // be removed or moved onto internals.runtimeFlags:
     void setAuthorShadowDOMForAnyElementEnabled(bool);
     void setLangAttributeAwareFormControlUIEnabled(bool);
     void setOverlayScrollbarsEnabled(bool);
     void setExperimentalContentSecurityPolicyFeaturesEnabled(bool);
     void setPseudoClassesInMatchingCriteriaInAuthorShadowTreesEnabled(bool);
     void setImageColorProfilesEnabled(bool);
     void setImageAnimationPolicy(const String&, ExceptionState&);
     void setScrollTopLeftInteropEnabled(bool);
+    void setLinkHeaderEnabled(bool);
 
     virtual void trace(Visitor*) override;
 
     void setAvailablePointerTypes(const String&, ExceptionState&);
     void setPrimaryPointerType(const String&, ExceptionState&);
     void setAvailableHoverTypes(const String&, ExceptionState&);
     void setPrimaryHoverType(const String&, ExceptionState&);
     void setDnsPrefetchLogging(bool, ExceptionState&);
 
 private:
     explicit InternalSettings(Page&);
 
     Settings* settings() const;
     Page* page() const { return m_page; }
     static const char* supplementName();
 
     RawPtrWillBeWeakMember<Page> m_page;
     Backup m_backup;
 };
 
 } // namespace blink
 
 #endif // InternalSettings_h