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

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

Index: third_party/WebKit/Source/core/dom/Element.h
diff --git a/third_party/WebKit/Source/core/dom/Element.h b/third_party/WebKit/Source/core/dom/Element.h
index 240ec279fd27930c3ebc18d8a715b73653b1d06e..342bb09c8184ba76f0b520327dbfd9d0113a1bea 100644
--- a/third_party/WebKit/Source/core/dom/Element.h
+++ b/third_party/WebKit/Source/core/dom/Element.h
@@ -410,11 +410,14 @@ public:
     // 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);
@@ -583,11 +586,13 @@ protected:
 
     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