Release mouse pointer capture when it starts drag

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

 /*
  * Copyright (C) 2006, 2007, 2009, 2010, 2011 Apple Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
  * 2. Redistributions in binary form must reproduce the above copyright
  *    notice, this list of conditions and the following disclaimer in the
@@ skipping 127 matching lines @@
   // the given node or a reasonable default (focus/last clicked).
   bool BubblingScroll(ScrollDirection,
                       ScrollGranularity,
                       Node* starting_node = nullptr);
 
   WebInputEventResult HandleMouseMoveEvent(
       const WebMouseEvent&,
       const Vector<WebMouseEvent>& coalesced_events);
   void HandleMouseLeaveEvent(const WebMouseEvent&);
 
+  WebInputEventResult HandlePointerEvent(const WebPointerEvent&, Node* target);
+
   WebInputEventResult HandleMousePressEvent(const WebMouseEvent&);
   WebInputEventResult HandleMouseReleaseEvent(const WebMouseEvent&);
   WebInputEventResult HandleWheelEvent(const WebMouseWheelEvent&);
 
   // Called on the local root frame exactly once per gesture event.
   WebInputEventResult HandleGestureEvent(const WebGestureEvent&);
   WebInputEventResult HandleGestureEvent(const GestureEventWithHitTestResults&);
 
   // Clear the old hover/active state within frames before moving the hover
   // state to the another frame
@@ skipping 230 matching lines @@
 
   // Set on GestureTapDown if the |pointerdown| event corresponding to the
   // triggering |touchstart| event was canceled. This suppresses mouse event
   // firing for the current gesture sequence (i.e. until next GestureTapDown).
   bool suppress_mouse_events_from_gestures_;
 };
 
 }  // namespace blink
 
 #endif  // EventHandler_h