Setting the link title may change the preferred set.

third_party/WebKit/Source/core/dom/StyleEngine.h

 /*
  * Copyright (C) 1999 Lars Knoll (knoll@kde.org)
  *           (C) 1999 Antti Koivisto (koivisto@kde.org)
  *           (C) 2001 Dirk Mueller (mueller@kde.org)
  *           (C) 2006 Alexey Proskuryakov (ap@webkit.org)
  * Copyright (C) 2004, 2005, 2006, 2007, 2008, 2009, 2010, 2012 Apple Inc. All rights reserved.
  * Copyright (C) 2008, 2009 Torch Mobile Inc. All rights reserved. (http://www.torchmobile.com/)
  * Copyright (C) 2010 Nokia Corporation and/or its subsidiary(-ies)
  * Copyright (C) 2011 Google Inc. All rights reserved.
  *
@@ skipping 80 matching lines @@
     void modifiedStyleSheetCandidateNode(Node*);
     void watchedSelectorsChanged();
 
     void injectAuthorSheet(StyleSheetContents* authorSheet);
     CSSStyleSheet& ensureInspectorStyleSheet();
 
     void clearMediaQueryRuleSetStyleSheets();
     void updateStyleSheetsInImport(DocumentStyleSheetCollector& parentCollector);
     void updateActiveStyleSheets(StyleResolverUpdateMode);
 
+    enum ActiveSheetsUpdate { DontUpdateActiveSheets, UpdateActiveSheets };
     String preferredStylesheetSetName() const { return m_preferredStylesheetSetName; }
     String selectedStylesheetSetName() const { return m_selectedStylesheetSetName; }
-    void setPreferredStylesheetSetNameIfNotSet(const String&);
+    void setPreferredStylesheetSetNameIfNotSet(const String&, ActiveSheetsUpdate);
     void setSelectedStylesheetSetName(const String&);
     void setHttpDefaultStyle(const String&);
 
     void addPendingSheet(StyleEngineContext&);
     void removePendingSheet(Node* styleSheetCandidateNode, const StyleEngineContext&);
 
     bool hasPendingScriptBlockingSheets() const { return m_pendingScriptBlockingStylesheets > 0; }
     bool hasPendingRenderBlockingSheets() const { return m_pendingRenderBlockingStylesheets > 0; }
     bool haveScriptBlockingStylesheetsLoaded() const { return !hasPendingScriptBlockingSheets() || m_ignorePendingStylesheets; }
     bool haveRenderBlockingStylesheetsLoaded() const { return !hasPendingRenderBlockingSheets() || m_ignorePendingStylesheets; }
@@ skipping 162 matching lines @@
 
     std::unique_ptr<StyleResolverStats> m_styleResolverStats;
     unsigned m_styleForElementCount = 0;
 
     friend class StyleEngineTest;
 };
 
 } // namespace blink
 
 #endif