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

third_party/WebKit/public/web/WebAXObject.h

Index: third_party/WebKit/public/web/WebAXObject.h
diff --git a/third_party/WebKit/public/web/WebAXObject.h b/third_party/WebKit/public/web/WebAXObject.h
index 124f6ceffebbd699ebd7583d52a1e35aa35bb10a..afb2bb5a81d0f682783632675f1d0d4fd016b77e 100644
--- a/third_party/WebKit/public/web/WebAXObject.h
+++ b/third_party/WebKit/public/web/WebAXObject.h
@@ -53,6 +53,7 @@ class WebNode;
 class WebDocument;
 class WebString;
 class WebURL;
+struct WebFloatRect;
 struct WebPoint;
 struct WebRect;
 
@@ -144,7 +145,6 @@ public:
     BLINK_EXPORT bool isMultiline() const;
     BLINK_EXPORT bool isRichlyEditable() const;
     BLINK_EXPORT bool ariaOwns(WebVector<WebAXObject>& ownsElements) const;
-    BLINK_EXPORT WebRect boundingBoxRect() const;
     BLINK_EXPORT WebString fontFamily() const;
     BLINK_EXPORT float fontSize() const;
     BLINK_EXPORT bool canvasHasFallbackContent() const;
@@ -289,7 +289,21 @@ public:
     BLINK_EXPORT WebPoint maximumScrollOffset() const;
     BLINK_EXPORT void setScrollOffset(const WebPoint&) const;
 
+    // Old bounds calculation interface. DEPRECATED, to be replaced with getRelativeBounds.
+    BLINK_EXPORT WebRect boundingBoxRect() const;
+
+    // NEW bounds calculation interface. Every object's bounding box is returned
+    // relative to a container object (which is guaranteed to be an ancestor) and
+    // optionally a transformation matrix that needs to be applied too.
+    // To compute the absolute bounding box of an element, start with its
+    // boundsInContainer and apply the transform. Then as long as its container is
+    // not null, walk up to its container and offset by the container's offset from
+    // origin, the container's scroll position if any, and apply the container's transform.
+    // Do this until you reach the root of the tree.
+    BLINK_EXPORT void getRelativeBounds(WebAXObject& offsetContainer, WebFloatRect& boundsInContainer, SkMatrix44& containerTransform) const;
+
     // Transformation relative to the parent frame, if local (otherwise returns identity).
+    // DEPRECATED, to be replaced with getRelativeBounds.
     BLINK_EXPORT SkMatrix44 transformFromLocalParentFrame() const;
 
     // Make this object visible by scrolling as many nested scrollable views as needed.