Implement accessibility support for CSS-transformed iframes.

third_party/WebKit/Source/modules/accessibility/AXLayoutObject.h

Index: third_party/WebKit/Source/modules/accessibility/AXLayoutObject.h
diff --git a/third_party/WebKit/Source/modules/accessibility/AXLayoutObject.h b/third_party/WebKit/Source/modules/accessibility/AXLayoutObject.h
index 87036495f18d73fcfb8dc1494496c92057f465e2..b7ec80c674b6ab0cfaebfd1e2d1c02f3126feddc 100644
--- a/third_party/WebKit/Source/modules/accessibility/AXLayoutObject.h
+++ b/third_party/WebKit/Source/modules/accessibility/AXLayoutObject.h
@@ -57,6 +57,7 @@ public:
     LayoutObject* getLayoutObject() const final { return m_layoutObject; }
     LayoutRect elementRect() const override;
     LayoutBoxModelObject* getLayoutBoxModelObject() const;
+    SkMatrix44 transformFromLocalParentFrame() const override;
     bool shouldNotifyActiveDescendant() const;
     ScrollableArea* getScrollableAreaIfScrollable() const final;
     AccessibilityRole determineAccessibilityRole() override;