[selectors4] Implement :focus-within pseudo-class

third_party/WebKit/Source/core/css/parser/CSSSelectorParser.cpp

 // Copyright 2014 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "core/css/parser/CSSSelectorParser.h"
 
 #include "core/css/CSSSelectorList.h"
 #include "core/css/StyleSheetContents.h"
 #include "core/css/parser/CSSParserContext.h"
 #include "core/frame/Deprecation.h"
@@ skipping 155 matching lines @@
       return true;
     default:
       return false;
   }
 }
 
 bool IsUserActionPseudoClass(CSSSelector::PseudoType pseudo) {
   switch (pseudo) {
     case CSSSelector::kPseudoHover:
     case CSSSelector::kPseudoFocus:
+    case CSSSelector::kPseudoFocusWithin:
     case CSSSelector::kPseudoActive:
       return true;
     default:
       return false;
   }
 }
 
 bool IsPseudoClassValidAfterPseudoElement(
     CSSSelector::PseudoType pseudo_class,
     CSSSelector::PseudoType compound_pseudo_element) {
@@ skipping 250 matching lines @@
     return nullptr;
 
   std::unique_ptr<CSSParserSelector> selector = CSSParserSelector::Create();
   selector->SetMatch(colons == 1 ? CSSSelector::kPseudoClass
                                  : CSSSelector::kPseudoElement);
 
   AtomicString value = token.Value().ToAtomicString().LowerASCII();
   bool has_arguments = token.GetType() == kFunctionToken;
   selector->UpdatePseudoType(value, has_arguments);
 
+  if (!RuntimeEnabledFeatures::cssSelectorsFocusWithinEnabled() &&
+      selector->GetPseudoType() == CSSSelector::kPseudoFocusWithin)
+    return nullptr;
+
   if (selector->Match() == CSSSelector::kPseudoElement &&
       disallow_pseudo_elements_)
     return nullptr;
 
   if (token.GetType() == kIdentToken) {
     range.Consume();
     if (selector->GetPseudoType() == CSSSelector::kPseudoUnknown)
       return nullptr;
     return selector;
   }
@@ skipping 437 matching lines @@
       }
       if (current->Relation() == CSSSelector::kIndirectAdjacent)
         context_->Count(UseCounter::kCSSSelectorIndirectAdjacent);
       if (current->SelectorList())
         RecordUsageAndDeprecations(*current->SelectorList());
     }
   }
 }
 
 }  // namespace blink