Implement nameFromLabelElement to see if a control is associated with a label.

third_party/WebKit/Source/modules/accessibility/AXNodeObject.cpp

 /*
  * Copyright (C) 2012, Google Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  *
  * 1.  Redistributions of source code must retain the above copyright
  *     notice, this list of conditions and the following disclaimer.
  * 2.  Redistributions in binary form must reproduce the above copyright
@@ skipping 155 matching lines @@
 
     // If this element is within a parent that cannot have children, it should not be exposed.
     if (isDescendantOfLeafNode()) {
         if (ignoredReasons)
             ignoredReasons->append(IgnoredReason(AXAncestorIsLeafNode, leafNodeAncestor()));
         return true;
     }
 
     // Ignore labels that are already referenced by a control.
     AXObject* controlObject = correspondingControlForLabelElement();
-    if (controlObject && controlObject->isCheckboxOrRadio()) {
-        AXNameFrom controlNameFrom;
-        AXObject::AXObjectVector controlNameObjects;
-        controlObject->name(controlNameFrom, &controlNameObjects);
-        if (controlNameFrom == AXNameFromRelatedElement) {
-            if (ignoredReasons) {
-                HTMLLabelElement* label = labelElementContainer();
-                if (label && !label->isSameNode(node())) {
-                    AXObject* labelAXObject = axObjectCache().getOrCreate(label);
-                    ignoredReasons->append(IgnoredReason(AXLabelContainer, labelAXObject));
-                }
+    if (controlObject && controlObject->isCheckboxOrRadio() && controlObject->nameFromLabelElement()) {
+        if (ignoredReasons) {
+            HTMLLabelElement* label = labelElementContainer();
+            if (label && !label->isSameNode(node())) {
+                AXObject* labelAXObject = axObjectCache().getOrCreate(label);
+                ignoredReasons->append(IgnoredReason(AXLabelContainer, labelAXObject));
+            }
 
-                ignoredReasons->append(IgnoredReason(AXLabelFor, controlObject));
-            }
-            return true;
+            ignoredReasons->append(IgnoredReason(AXLabelFor, controlObject));
         }
+        return true;
     }
 
     Element* element = node()->isElementNode() ? toElement(node()) : node()->parentElement();
     if (!layoutObject()
         && (!element || !element->isInCanvasSubtree())
         && !equalIgnoringCase(getAttribute(aria_hiddenAttr), "false")) {
         if (ignoredReasons)
             ignoredReasons->append(IgnoredReason(AXNotRendered));
         return true;
     }
@@ skipping 1407 matching lines @@
         }
 
         String result = recursiveTextAlternative(*child, false, visited);
         accumulatedText.append(result);
         previous = child;
     }
 
     return accumulatedText.toString();
 }
 
+bool AXNodeObject::nameFromLabelElement() const
+{
+    // This unfortunately duplicates a bit of logic from textAlternative and nativeTextAlternative,
+    // but it's necessary because nameFromLabelElement needs to be called from
+    // computeAccessibilityIsIgnored, which isn't allowed to call axObjectCache->getOrCreate.
+
+    if (!node() && !layoutObject())
+        return false;
+
+    // Step 2A from: http://www.w3.org/TR/accname-aam-1.1
+    if (layoutObject()
+        && layoutObject()->style()->visibility() != VISIBLE
+        && !equalIgnoringCase(getAttribute(aria_hiddenAttr), "false")) {
+        return false;
+    }
+
+    // Step 2B from: http://www.w3.org/TR/accname-aam-1.1
+    WillBeHeapVector<RawPtrWillBeMember<Element>> elements;
+    ariaLabelledbyElementVector(elements);
+    if (elements.size() > 0)
+        return false;
+
+    // Step 2C from: http://www.w3.org/TR/accname-aam-1.1
+    const AtomicString& ariaLabel = getAttribute(aria_labelAttr);
+    if (!ariaLabel.isEmpty())
+        return false;
+
+    // Based on http://rawgit.com/w3c/aria/master/html-aam/html-aam.html#accessible-name-and-description-calculation
+    // 5.1/5.5 Text inputs, Other labelable Elements
+    HTMLElement* htmlElement = nullptr;
+    if (node()->isHTMLElement())
+        htmlElement = toHTMLElement(node());
+    if (htmlElement && htmlElement->isLabelable()) {
+        HTMLLabelElement* label = labelForElement(htmlElement);
+        if (label)
+            return true;
+    }
+
+    return false;
+}
+
 LayoutRect AXNodeObject::elementRect() const
 {
     // First check if it has a custom rect, for example if this element is tied to a canvas path.
     if (!m_explicitElementRect.isEmpty())
         return m_explicitElementRect;
 
     // FIXME: If there are a lot of elements in the canvas, it will be inefficient.
     // We can avoid the inefficient calculations by using AXComputedObjectAttributeCache.
     if (node()->parentElement()->isInCanvasSubtree()) {
         LayoutRect rect;
@@ skipping 429 matching lines @@
         ASSERT(relatedObjects);
 
     String textAlternative;
     AXRelatedObjectVector localRelatedObjects;
 
     const HTMLInputElement* inputElement = nullptr;
     if (isHTMLInputElement(node()))
         inputElement = toHTMLInputElement(node());
 
     // 5.1/5.5 Text inputs, Other labelable Elements
+    // If you change this logic, update AXNodeObject::nameFromLabelElement, too.
     HTMLElement* htmlElement = nullptr;
     if (node()->isHTMLElement())
         htmlElement = toHTMLElement(node());
     if (htmlElement && htmlElement->isLabelable()) {
         // label
         nameFrom = AXNameFromRelatedElement;
         if (nameSources) {
             nameSources->append(NameSource(*foundTextAlternative));
             nameSources->last().type = nameFrom;
             nameSources->last().nativeSource = AXTextFromNativeHTMLLabel;
@@ skipping 569 matching lines @@
     return placeholder;
 }
 
 DEFINE_TRACE(AXNodeObject)
 {
     visitor->trace(m_node);
     AXObject::trace(visitor);
 }
 
 } // namespace blin