Make sure Document::updateLayoutTree*() is called before Element::isFocusable().

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

 /*
  * Copyright (C) 1999 Lars Knoll (knoll@kde.org)
  *           (C) 1999 Antti Koivisto (koivisto@kde.org)
  *           (C) 2001 Peter Kelly (pmk@post.com)
  *           (C) 2001 Dirk Mueller (mueller@kde.org)
  * Copyright (C) 2003-2011, 2013, 2014 Apple Inc. All rights reserved.
  *
  * This library is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Library General Public
  * License as published by the Free Software Foundation; either
@@ skipping 392 matching lines @@
     void nativeApplyScroll(ScrollState&);
 
     void callDistributeScroll(ScrollState&);
     void callApplyScroll(ScrollState&);
 
     // Whether this element can receive focus at all. Most elements are not
     // focusable but some elements, such as form controls and links, are. Unlike
     // layoutObjectIsFocusable(), this method may be called when layout is not up to
     // date, so it must not use the layoutObject to determine focusability.
     virtual bool supportsFocus() const;
-    // Whether the node can actually be focused.
+    // Whether the node can actually be focused.  Callers should ensure
+    // ComputedStyle is up to date;
+    // e.g. Calling Document::updateLayoutTreeIgnorePendingStylesheets().

[falken, 2016/02/05 04:42:40]

comment nits: one space after period is consistent with rest of comment, and
"Calling" -> "by calling" seems better.

[tkent, 2016/02/05 04:57:45]

Done.

     bool isFocusable() const;
-    bool isFocusedElementInDocument() const;
     virtual bool isKeyboardFocusable() const;
     virtual bool isMouseFocusable() const;
+    bool isFocusedElementInDocument() const;
+
     virtual void dispatchFocusEvent(Element* oldFocusedElement, WebFocusType, InputDeviceCapabilities* sourceCapabilities = nullptr);
     virtual void dispatchBlurEvent(Element* newFocusedElement, WebFocusType, InputDeviceCapabilities* sourceCapabilities = nullptr);
     virtual void dispatchFocusInEvent(const AtomicString& eventType, Element* oldFocusedElement, WebFocusType, InputDeviceCapabilities* sourceCapabilities = nullptr);
     void dispatchFocusOutEvent(const AtomicString& eventType, Element* newFocusedElement, InputDeviceCapabilities* sourceCapabilities = nullptr);
 
     String innerText();
     String outerText();
     String innerHTML() const;
     String outerHTML() const;
     void setInnerHTML(const String&, ExceptionState&);
@@ skipping 148 matching lines @@
     virtual void didRecalcStyle(StyleRecalcChange);
     virtual PassRefPtr<ComputedStyle> customStyleForLayoutObject();
 
     virtual bool shouldRegisterAsNamedItem() const { return false; }
     virtual bool shouldRegisterAsExtraNamedItem() const { return false; }
 
     bool supportsSpatialNavigationFocus() const;
 
     void clearTabIndexExplicitlyIfNeeded();
     void setTabIndexExplicitly(short);
-    // Subclasses may override this method to affect focusability. Unlike
-    // supportsFocus, this method must be called on an up-to-date layout, so it
-    // may use the layoutObject to reason about focusability. This method cannot be
-    // moved to LayoutObject because some focusable nodes don't have layoutObjects,
-    // e.g., HTMLOptionElement.
+    // Subclasses may override this method to affect focusability. This method
+    // must be called on an up-to-date ComputedStyle, so it may use existence of
+    // layoutObject and the LayoutObject::style() to reason about focusability.
+    // However, we must not retrieve layout information like position and size.

[falken, 2016/02/05 04:42:40]

"we" -> "it" is more consistent with the previous sentence

[tkent, 2016/02/05 04:57:45]

Done.

+    // This method cannot be moved to LayoutObject because some focusable nodes
+    // don't have layoutObjects. e.g., HTMLOptionElement.
+    // TODO(tkent): Rename this to isFocusableStyle.

[falken, 2016/02/05 04:42:40]

good idea!

     virtual bool layoutObjectIsFocusable() const;
 
     // classAttributeChanged() exists to share code between
     // parseAttribute (called via setAttribute()) and
     // svgAttributeChanged (called when element.className.baseValue is set)
     void classAttributeChanged(const AtomicString& newClassString);
 
     static bool attributeValueIsJavaScriptURL(const Attribute&);
 
     PassRefPtr<ComputedStyle> originalStyleForLayoutObject();
@@ skipping 338 matching lines @@
     static PassRefPtrWillBeRawPtr<T> create(const QualifiedName&, Document&)
 #define DEFINE_ELEMENT_FACTORY_WITH_TAGNAME(T) \
     PassRefPtrWillBeRawPtr<T> T::create(const QualifiedName& tagName, Document& document) \
     { \
         return adoptRefWillBeNoop(new T(tagName, document)); \
     }
 
 } // namespace blink
 
 #endif // Element_h