Migrating ErrorMessage method from AXLayoutObject to AXNodeObject.

AX-Relnotes: N/A
Bug: 1093651
Change-Id: Iabc78cb0eb2ca3f583cf5eeaf8c07502d50da280
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2239142Reviewed-by: Meredith Lane <meredithl@chromium.org>
Reviewed-by: Alice Boxhall <aboxhall@chromium.org>
Commit-Queue: Chris Hall <chrishall@chromium.org>
Cr-Commit-Position: refs/heads/master@{#779182}

third_party/blink/renderer/modules/accessibility/ax_layout_object.cc

@@ -2060,22 +2060,6 @@ void AXLayoutObject::TextChanged() {
   AXNodeObject::TextChanged();
 }
 
-AXObject* AXLayoutObject::ErrorMessage() const {
-  // Check for aria-errormessage.
-  Element* existing_error_message =
-      GetAOMPropertyOrARIAAttribute(AOMRelationProperty::kErrorMessage);
-  if (existing_error_message)
-    return AXObjectCache().GetOrCreate(existing_error_message);
-
-  // Check for visible validationMessage. This can only be visible for a focused
-  // control. Corollary: if there is a visible validationMessage alert box, then
-  // it is related to the current focus.
-  if (this != AXObjectCache().FocusedObject())
-    return nullptr;
-
-  return AXObjectCache().ValidationMessageObjectIfInvalid();
-}
-
 // The following is a heuristic used to determine if a
 // <table> should be with ax::mojom::blink::Role::kTable or
 // ax::mojom::blink::Role::kLayoutTable.

third_party/blink/renderer/modules/accessibility/ax_layout_object.h

@@ -176,10 +176,6 @@ class MODULES_EXPORT AXLayoutObject : public AXNodeObject {
   // For a table row or column.
   AXObject* HeaderObject() const override;
 
-  // The aria-errormessage object or native object from a validationMessage
-  // alert.
-  AXObject* ErrorMessage() const override;
-
   //
   // Layout object specific methods.
   //

third_party/blink/renderer/modules/accessibility/ax_node_object.cc

@@ -3700,6 +3700,22 @@ void AXNodeObject::TextChanged() {
   }
 }
 
+AXObject* AXNodeObject::ErrorMessage() const {
+  // Check for aria-errormessage.
+  Element* existing_error_message =
+      GetAOMPropertyOrARIAAttribute(AOMRelationProperty::kErrorMessage);
+  if (existing_error_message)
+    return AXObjectCache().GetOrCreate(existing_error_message);
+
+  // Check for visible validationMessage. This can only be visible for a focused
+  // control. Corollary: if there is a visible validationMessage alert box, then
+  // it is related to the current focus.
+  if (this != AXObjectCache().FocusedObject())
+    return nullptr;
+
+  return AXObjectCache().ValidationMessageObjectIfInvalid();
+}
+
 void AXNodeObject::ComputeAriaOwnsChildren(
     HeapVector<Member<AXObject>>& owned_children) const {
   Vector<String> id_vector;

third_party/blink/renderer/modules/accessibility/ax_node_object.h

@@ -241,6 +241,10 @@ class MODULES_EXPORT AXNodeObject : public AXObject {
   void SelectionChanged() final;
   void TextChanged() override;
 
+  // The aria-errormessage object or native object from a validationMessage
+  // alert.
+  AXObject* ErrorMessage() const override;
+
   // Position in set and Size of set
   int PosInSet() const override;
   int SetSize() const override;