Tidy DEFINE_(THREAD_SAFE_)STATIC_LOCAL() implementations.

third_party/WebKit/Source/core/html/HTMLTableElement.cpp

 /*
  * Copyright (C) 1997 Martin Jones (mjones@kde.org)
  *           (C) 1997 Torben Weis (weis@kde.org)
  *           (C) 1998 Waldo Bastian (bastian@kde.org)
  *           (C) 1999 Lars Knoll (knoll@kde.org)
  *           (C) 1999 Antti Koivisto (koivisto@kde.org)
  * Copyright (C) 2003, 2004, 2005, 2006, 2008, 2010, 2011 Apple Inc. All rights
  * reserved.
  *
  * This library is free software; you can redistribute it and/or
@@ skipping 435 matching lines @@
 
 const StylePropertySet*
 HTMLTableElement::additionalPresentationAttributeStyle() {
   if (m_frameAttr)
     return nullptr;
 
   if (!m_borderAttr && !m_borderColorAttr) {
     // Setting the border to 'hidden' allows it to win over any border
     // set on the table's cells during border-conflict resolution.
     if (m_rulesAttr != UnsetRules) {
+      // Note: this (Mutable)StylePropertySet singleton has an embedded
+      // CSSStyleDeclaration reference (m_cssomWrapper), which is a
+      // ScriptWrappable (=> it can have a v8 wrapper object). Exposing
+      // and sharing those via static locals is unsafe, as the singleton
+      // really is accessible across window contexts within a renderer
+      // process.
+      //
+      // However, that CSSStyleDeclaration is never instantiated for these
+      // presentation attribute style properties, hence this singleton (and
+      // the ones below) are considered safe. Indicate that by disabling
+      // the no-ScriptWrappables-in-singletons verification check.

[haraken, 2017/02/11 10:25:20]

Your analysis looks correct, but it looks better to avoid using
DEFINE_STATIC_LOCAL... by e.g., associating the StylePropertySet with Document
(or StyleEngine) etc.

[sof, 2017/02/11 12:09:11]

That could probably be done without it being too ad-hoc.

       DEFINE_STATIC_LOCAL(StylePropertySet, solidBorderStyle,
-                          (createBorderStyle(CSSValueHidden)));
+                          (createBorderStyle(CSSValueHidden)),
+                          CheckScriptWrappable::No);
       return &solidBorderStyle;
     }
     return nullptr;
   }
 
   if (m_borderColorAttr) {
     DEFINE_STATIC_LOCAL(StylePropertySet, solidBorderStyle,
-                        (createBorderStyle(CSSValueSolid)));
+                        (createBorderStyle(CSSValueSolid)),
+                        CheckScriptWrappable::No);
     return &solidBorderStyle;
   }
   DEFINE_STATIC_LOCAL(StylePropertySet, outsetBorderStyle,
-                      (createBorderStyle(CSSValueOutset)));
+                      (createBorderStyle(CSSValueOutset)),
+                      CheckScriptWrappable::No);
   return &outsetBorderStyle;
 }
 
 HTMLTableElement::CellBorders HTMLTableElement::getCellBorders() const {
   switch (m_rulesAttr) {
     case NoneRules:
     case GroupsRules:
       return NoBorders;
     case AllRules:
       return SolidBorders;
@@ skipping 83 matching lines @@
   }
   return style;
 }
 
 const StylePropertySet* HTMLTableElement::additionalGroupStyle(bool rows) {
   if (m_rulesAttr != GroupsRules)
     return nullptr;
 
   if (rows) {
     DEFINE_STATIC_LOCAL(StylePropertySet, rowBorderStyle,
-                        (createGroupBorderStyle(true)));
+                        (createGroupBorderStyle(true)),
+                        CheckScriptWrappable::No);
     return &rowBorderStyle;
   }
   DEFINE_STATIC_LOCAL(StylePropertySet, columnBorderStyle,
-                      (createGroupBorderStyle(false)));
+                      (createGroupBorderStyle(false)),
+                      CheckScriptWrappable::No);
   return &columnBorderStyle;
 }
 
 bool HTMLTableElement::isURLAttribute(const Attribute& attribute) const {
   return attribute.name() == backgroundAttr ||
          HTMLElement::isURLAttribute(attribute);
 }
 
 bool HTMLTableElement::hasLegalLinkAttribute(const QualifiedName& name) const {
   return name == backgroundAttr || HTMLElement::hasLegalLinkAttribute(name);
@@ skipping 18 matching lines @@
 const AtomicString& HTMLTableElement::summary() const {
   return getAttribute(summaryAttr);
 }
 
 DEFINE_TRACE(HTMLTableElement) {
   visitor->trace(m_sharedCellStyle);
   HTMLElement::trace(visitor);
 }
 
 }  // namespace blink