Tie DragState to DragController.

third_party/WebKit/Source/core/page/DragController.h

Index: third_party/WebKit/Source/core/page/DragController.h
diff --git a/third_party/WebKit/Source/core/page/DragController.h b/third_party/WebKit/Source/core/page/DragController.h
index 763f6576dcffc8644d4937aa16b6f0e788e7db85..23325dabaec12a0434c8a941ea09e41ab6d01c30 100644
--- a/third_party/WebKit/Source/core/page/DragController.h
+++ b/third_party/WebKit/Source/core/page/DragController.h
@@ -79,10 +79,12 @@ class CORE_EXPORT DragController final
                  const WebMouseEvent& dragEvent,
                  const IntPoint& dragOrigin);
 
+  DragState& dragState();
+
   DECLARE_TRACE();
 
  private:
-  DragController(Page*);
+  explicit DragController(Page*);
 
   DispatchEventResult dispatchTextInputEventFor(LocalFrame*, DragData*);
   bool canProcessDrag(DragData*, LocalFrame& localRoot);
@@ -114,6 +116,8 @@ class CORE_EXPORT DragController final
   // The Document (if any) that initiated the drag.
   Member<Document> m_dragInitiator;
 
+  Member<DragState> m_dragState;
+
   Member<HTMLInputElement> m_fileInputElementUnderMouse;
   bool m_documentIsHandlingDrag;