Add interface to get relative bounding box rect of AX objects.

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

 /*
  * Copyright (C) 2008, 2009, 2011 Apple 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 1331 matching lines @@
 void AXObject::setScrollOffset(const IntPoint& offset) const
 {
     ScrollableArea* area = getScrollableAreaIfScrollable();
     if (!area)
         return;
 
     // TODO(bokan): This should potentially be a UserScroll.
     area->setScrollPosition(DoublePoint(offset.x(), offset.y()), ProgrammaticScroll);
 }
 
+void AXObject::getRelativeBounds(AXObject** container, FloatRect& boundsInContainer, SkMatrix44& containerTransform) const
+{
+    *container = nullptr;
+    boundsInContainer = FloatRect();
+    containerTransform.setIdentity();
+}
+
 //
 // Modify or take an action on an object.
 //
 
 bool AXObject::press() const
 {
     Element* actionElem = actionElement();
     if (!actionElem)
         return false;
     UserGestureIndicator gestureIndicator(DefinitelyProcessingNewUserGesture);
@@ skipping 381 matching lines @@
 
 DEFINE_TRACE(AXObject)
 {
     visitor->trace(m_children);
     visitor->trace(m_parent);
     visitor->trace(m_cachedLiveRegionRoot);
     visitor->trace(m_axObjectCache);
 }
 
 } // namespace blink