Release mouse pointer capture when it starts drag

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

 // 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.
 
 #ifndef PointerEventManager_h
 #define PointerEventManager_h
 
 #include "core/CoreExport.h"
 #include "core/events/PointerEvent.h"
 #include "core/events/PointerEventFactory.h"
@@ skipping 12 matching lines @@
 // This class takes care of dispatching all pointer events and keeps track of
 // properties of active pointer events.
 class CORE_EXPORT PointerEventManager
     : public GarbageCollectedFinalized<PointerEventManager> {
   WTF_MAKE_NONCOPYABLE(PointerEventManager);
 
  public:
   PointerEventManager(LocalFrame&, MouseEventManager&);
   DECLARE_TRACE();
 
+  // This is the unified path for handling all input device events. This may
+  // cause firing DOM pointerevents, mouseevent, and touch events accordingly.

[mustaq, 2017/07/10 16:17:30]

Say it's a WIP, link to the bug (we have one, right?).

[Navid Zolghadr, 2017/07/11 15:41:06]

Done.

+  WebInputEventResult HandlePointerEvent(const WebPointerEvent&, Node* target);
+
   // Sends the mouse pointer events and the boundary events
   // that it may cause. It also sends the compat mouse events
   // and sets the newNodeUnderMouse if the capturing is set
   // in this function.
   WebInputEventResult SendMousePointerEvent(
       Node* target,
       const String& canvas_region_id,
       const AtomicString& type,
       const WebMouseEvent&,
       const Vector<WebMouseEvent>& coalesced_events);
@@ skipping 189 matching lines @@
   Member<MouseEventManager> mouse_event_manager_;
 
   // The pointerId of the PointerEvent currently being dispatched within this
   // frame or 0 if none.
   int dispatching_pointer_id_;
 };
 
 }  // namespace blink
 
 #endif  // PointerEventManager_h