Account for mouse leave events in dragging flow

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 700 matching lines @@
   //    is on a mouse press. The problem is the <embed> node only starts
   //    capturing mouse events *after* m_mousePressed for the containing frame
   //    has already been set to true. As a result, the frame's EventHandler
   //    never sees the mouse release event, which is supposed to reset
   //    m_mousePressed... so m_mousePressed ends up remaining true until the
   //    event handler finally gets another mouse released event. Oops.
   // 2. Dragging doesn't start until after a mouse press event, but a drag
   //    that ends as a result of a mouse release does not send a mouse release
   //    event. As a result, m_mousePressed also ends up remaining true until
   //    the next mouse release event seen by the EventHandler.
-  if (event.Event().button != WebPointerProperties::Button::kLeft)
+  // 3. When pressing Esc key while dragging and the object is outside of the
+  //    we get a mouse leave event here
+  if (event.Event().button != WebPointerProperties::Button::kLeft ||
+      event.Event().GetType() == WebInputEvent::kMouseLeave)
     mouse_pressed_ = false;
 
   if (!mouse_pressed_)
     return WebInputEventResult::kNotHandled;
 
   if (HandleDrag(event, DragInitiator::kMouse))
     return WebInputEventResult::kHandledSystem;
 
   Node* target_node = event.InnerNode();
   if (!target_node)
@@ skipping 318 matching lines @@
 
 void MouseEventManager::SetClickCount(int click_count) {
   click_count_ = click_count;
 }
 
 bool MouseEventManager::MouseDownMayStartDrag() {
   return mouse_down_may_start_drag_;
 }
 
 }  // namespace blink