Current work-in-progress crbug.com/567021

third_party/WebKit/Source/core/css/StyleSheetContents.h

Index: third_party/WebKit/Source/core/css/StyleSheetContents.h
diff --git a/third_party/WebKit/Source/core/css/StyleSheetContents.h b/third_party/WebKit/Source/core/css/StyleSheetContents.h
index c9ef7b2093508c58d2d0c15443de88d06698a4a1..b450b3303f8e817d60d0a7f7253e43f17c3396b8 100644
--- a/third_party/WebKit/Source/core/css/StyleSheetContents.h
+++ b/third_party/WebKit/Source/core/css/StyleSheetContents.h
@@ -91,10 +91,13 @@ public:
     void setHasSyntacticallyValidCSSHeader(bool isValidCss);
     bool hasSyntacticallyValidCSSHeader() const { return m_hasSyntacticallyValidCSSHeader; }
 
-    void setHasFontFaceRule(bool b) { m_hasFontFaceRule = b; }
+    void setHasFontFaceRule() { m_hasFontFaceRule = true; }
     bool hasFontFaceRule() const { return m_hasFontFaceRule; }
     void findFontFaceRules(HeapVector<Member<const StyleRuleFontFace>>& fontFaceRules);
 
+    void setHasViewportRule() { m_hasViewportRule = true; }
+    bool hasViewportRule() const { return m_hasViewportRule; }
+
     void parserAddNamespace(const AtomicString& prefix, const AtomicString& uri);
     void parserAppendRule(StyleRuleBase*);
 
@@ -153,6 +156,7 @@ public:
 
     RuleSet& ruleSet() { ASSERT(m_ruleSet); return *m_ruleSet.get(); }
     RuleSet& ensureRuleSet(const MediaQueryEvaluator&, AddRuleFlags);
+    RuleSet& ensureEmptyRuleSet();
     void clearRuleSet();
 
     String sourceMapURL() const { return m_sourceMapURL; }
@@ -184,6 +188,7 @@ private:
     bool m_didLoadErrorOccur : 1;
     bool m_isMutable : 1;
     bool m_hasFontFaceRule : 1;
+    bool m_hasViewportRule : 1;
     bool m_hasMediaQueries : 1;
     bool m_hasSingleOwnerDocument : 1;