Ensure that the auto scroll state in the AutoscrollController is cleared if the scroll operation cl…

third_party/WebKit/Source/core/page/AutoscrollController.cpp

Index: third_party/WebKit/Source/core/page/AutoscrollController.cpp
diff --git a/third_party/WebKit/Source/core/page/AutoscrollController.cpp b/third_party/WebKit/Source/core/page/AutoscrollController.cpp
index 38650aaf05c81d52b2e435a7bc625e765b137ce0..a3f79c56c73840bd5241b8430a13a96a0c798497 100644
--- a/third_party/WebKit/Source/core/page/AutoscrollController.cpp
+++ b/third_party/WebKit/Source/core/page/AutoscrollController.cpp
@@ -131,7 +131,12 @@ void AutoscrollController::updateAutoscrollLayoutObject()
 
     while (layoutObject && !(layoutObject->isBox() && toLayoutBox(layoutObject)->canAutoscroll()))
         layoutObject = layoutObject->parent();
-    m_autoscrollLayoutObject = layoutObject && layoutObject->isBox() ? toLayoutBox(layoutObject) : nullptr;
+
+    LayoutBox* autoscrollLayoutObject = layoutObject && layoutObject->isBox() ? toLayoutBox(layoutObject) : nullptr;
+    if (m_autoscrollLayoutObject && !autoscrollLayoutObject)
+        stopAutoscrollIfNeeded(m_autoscrollLayoutObject);
+
+    m_autoscrollLayoutObject = autoscrollLayoutObject;
 }
 
 void AutoscrollController::updateDragAndDrop(Node* dropTargetNode, const IntPoint& eventPosition, double eventTime)