Fix draggable elements are painted at incorrect position

third_party/WebKit/Source/core/input/EventHandler.cpp

Index: third_party/WebKit/Source/core/input/EventHandler.cpp
diff --git a/third_party/WebKit/Source/core/input/EventHandler.cpp b/third_party/WebKit/Source/core/input/EventHandler.cpp
index 188d4c4fab19cba46bedd6102aa61ee868924cc9..5cd29438afc881ad4bd40c9205cf36ecad63177e 100644
--- a/third_party/WebKit/Source/core/input/EventHandler.cpp
+++ b/third_party/WebKit/Source/core/input/EventHandler.cpp
@@ -687,6 +687,14 @@ IntPoint EventHandler::lastKnownMousePosition() const
     return m_lastKnownMousePosition;
 }
 
+IntPoint EventHandler::dragDataTransferLocationForTesting()
+{
+    if (dragState().m_dragDataTransfer)
+        return dragState().m_dragDataTransfer->dragLocation();
+
+    return IntPoint();
+}
+
 static LocalFrame* subframeForTargetNode(Node* node)
 {
     if (!node)
@@ -3321,8 +3329,8 @@ bool EventHandler::tryStartDrag(const MouseEventWithHitTestResults& event)
     // image and offset
     if (dragState().m_dragType == DragSourceActionDHTML) {
         if (LayoutObject* layoutObject = dragState().m_dragSrc->layoutObject()) {
-            FloatPoint absPos = layoutObject->localToAbsolute(FloatPoint(), UseTransforms);
-            IntSize delta = m_mouseDownPos - roundedIntPoint(absPos);
+            IntRect absoluteBoundingBox = layoutObject->absoluteBoundingBoxRect();

[fs, 2016/02/24 12:51:16]

Why did you switch this to absoluteBoundingBoxRect (from
absoluteBoundingBoxRectIncludingDescendants)?

[hyunjunekim2, 2016/02/24 13:06:36]

|absoluteBoundingBoxRect| function was thought to include both.
But re-change |absoluteBoundingBoxRectIncludingDescendants|.
Because |absoluteBoundingBoxRectIncludingDescendants| function contains
|absoluteBoundingBoxrect| Layer of children.

+            IntSize delta = m_mouseDownPos - absoluteBoundingBox.location();
             dragState().m_dragDataTransfer->setDragImageElement(dragState().m_dragSrc.get(), IntPoint(delta));
         } else {
             // The layoutObject has disappeared, this can happen if the onStartDrag handler has hidden