[selectors4] Implement :focus-within pseudo-class

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

 // 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.
 
 #ifndef StyleChangeReason_h
 #define StyleChangeReason_h
 
 #include "core/dom/QualifiedName.h"
 #include "wtf/text/AtomicString.h"
 #include "wtf/text/WTFString.h"
@@ skipping 37 matching lines @@
 extern const char kWritingModeChange[];
 extern const char kZoom[];
 }  // namespace StyleChangeReason
 typedef const char StyleChangeReasonString[];
 
 namespace StyleChangeExtraData {
 extern const AtomicString& g_active;
 extern const AtomicString& g_disabled;
 extern const AtomicString& g_drag;
 extern const AtomicString& g_focus;
+extern const AtomicString& g_focus_within;
 extern const AtomicString& g_hover;
 extern const AtomicString& g_past;
 extern const AtomicString& g_unresolved;
 
 void Init();
 }
 
 // |StyleChangeReasonForTracing| is used to trace the reason a
 // |Node::setNeedsStyleRecalc| call was made to show it in DevTools or in
 // about:tracing.
@@ skipping 32 matching lines @@
   void operator==(const StyleChangeReasonForTracing&) const {}
   void operator!=(const StyleChangeReasonForTracing&) const {}
 
   const char* reason_;
   AtomicString extra_data_;
 };
 
 }  // namespace blink
 
 #endif  // StyleChangeReason_h