Implement the inert attribute

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

Index: third_party/WebKit/Source/modules/accessibility/AXObject.cpp
diff --git a/third_party/WebKit/Source/modules/accessibility/AXObject.cpp b/third_party/WebKit/Source/modules/accessibility/AXObject.cpp
index 09e272689e20a0a091b1d4ddf465b1347b8c5ca3..26359cf99942ff77a0cdf4aa7154cf0f4844ac96 100644
--- a/third_party/WebKit/Source/modules/accessibility/AXObject.cpp
+++ b/third_party/WebKit/Source/modules/accessibility/AXObject.cpp
@@ -576,8 +576,11 @@ bool AXObject::computeIsInertOrAriaHidden(IgnoredReasons* ignoredReasons) const
                     else
                         ignoredReasons->append(IgnoredReason(AXInert));
                 } else {
-                    // TODO(aboxhall): handle inert attribute if it eventuates
-                    ignoredReasons->append(IgnoredReason(AXInert));
+                    const AXObject* inertRootEl = inertRoot();
+                    if (inertRootEl == this)
+                        ignoredReasons->append(IgnoredReason(AXInert));
+                    else
+                        ignoredReasons->append(IgnoredReason(AXInertRoot, inertRootEl));
                 }
             }
             return true;
@@ -633,6 +636,16 @@ const AXObject* AXObject::ariaHiddenRoot() const
     return 0;
 }
 
+const AXObject* AXObject::inertRoot() const
+{
+    for (const AXObject* object = this; object; object = object->parentObject()) {
+        if (object->hasAttribute(inertAttr))
+            return object;
+    }
+
+    return 0;
+}
+
 bool AXObject::isDescendantOfDisabledNode() const
 {
     updateCachedAttributeValuesIfNeeded();