MouseEventManager: reset drag state upon detaching.

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

 // Copyright 2016 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "core/input/MouseEventManager.h"
 
 #include "core/clipboard/DataObject.h"
 #include "core/clipboard/DataTransfer.h"
 #include "core/dom/Element.h"
 #include "core/dom/ElementTraversal.h"
@@ skipping 83 matching lines @@
   m_lastKnownMouseGlobalPosition = IntPoint();
   m_mousePressed = false;
   m_clickCount = 0;
   m_clickNode = nullptr;
   m_mouseDownPos = IntPoint();
   m_mouseDownTimestamp = TimeTicks();
   m_mouseDown = WebMouseEvent();
   m_svgPan = false;
   m_dragStartPos = LayoutPoint();
   m_fakeMouseMoveEventTimer.stop();
+  resetDragState();
 }
 
 MouseEventManager::~MouseEventManager() = default;
 
 DEFINE_TRACE(MouseEventManager) {
   visitor->trace(m_frame);
   visitor->trace(m_scrollManager);
   visitor->trace(m_nodeUnderMouse);
   visitor->trace(m_mousePressNode);
   visitor->trace(m_clickNode);
@@ skipping 925 matching lines @@
 
 void MouseEventManager::setClickCount(int clickCount) {
   m_clickCount = clickCount;
 }
 
 bool MouseEventManager::mouseDownMayStartDrag() {
   return m_mouseDownMayStartDrag;
 }
 
 }  // namespace blink