Implement accessibility support for CSS-transformed iframes.

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

Index: third_party/WebKit/Source/modules/accessibility/AXLayoutObject.cpp
diff --git a/third_party/WebKit/Source/modules/accessibility/AXLayoutObject.cpp b/third_party/WebKit/Source/modules/accessibility/AXLayoutObject.cpp
index 457b67eb20efffd9fed6453768d62a55c09f565a..b43f39edb7d524a07a06fdd0913f0f76aaedfa12 100644
--- a/third_party/WebKit/Source/modules/accessibility/AXLayoutObject.cpp
+++ b/third_party/WebKit/Source/modules/accessibility/AXLayoutObject.cpp
@@ -80,6 +80,7 @@
 #include "modules/accessibility/AXSpinButton.h"
 #include "modules/accessibility/AXTable.h"
 #include "platform/fonts/FontTraits.h"
+#include "platform/geometry/TransformState.h"
 #include "platform/text/PlatformLocale.h"
 #include "platform/text/TextDirection.h"
 #include "wtf/StdLibExtras.h"
@@ -218,6 +219,30 @@ LayoutRect AXLayoutObject::elementRect() const
     return m_cachedElementRect;
 }
 
+SkMatrix44 AXLayoutObject::localFrameRootTransform() const
+{
+    if (!m_layoutObject || !documentFrameView() || !documentFrameView()->layoutView())
+        return SkMatrix44();
+
+    TransformationMatrix accumulatedTransform;
+    LayoutObject* layoutObject = documentFrameView()->layoutView();
+    for (;;) {
+        LayoutObject* container = layoutObject->parent();
+        if (!container && layoutObject->frame())
+            container = layoutObject->frame()->ownerLayoutObject();
+        if (!container)
+            break;
+
+        LayoutSize offset = layoutObject->offsetFromContainer(container, LayoutPoint());
+        TransformationMatrix transformFromContainer;
+        layoutObject->getTransformFromContainer(container, offset, transformFromContainer);
+        accumulatedTransform *= transformFromContainer;
+        layoutObject = container;
+    }
+
+    return TransformationMatrix::toSkMatrix44(accumulatedTransform);
+}
+
 LayoutBoxModelObject* AXLayoutObject::layoutBoxModelObject() const
 {
     if (!m_layoutObject || !m_layoutObject->isBoxModelObject())