Fix button event on mouse events.

third_party/WebKit/Source/core/events/MouseEvent.cpp

 /*
  * Copyright (C) 2001 Peter Kelly (pmk@post.com)
  * Copyright (C) 2001 Tobias Anton (anton@stud.fbi.fh-darmstadt.de)
  * Copyright (C) 2006 Samuel Weinig (sam.weinig@gmail.com)
  * Copyright (C) 2003, 2005, 2006, 2008 Apple Inc. All rights reserved.
  *
  * This library is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Library General Public
  * License as published by the Free Software Foundation; either
  * version 2 of the License, or (at your option) any later version.
@@ skipping 60 matching lines @@
   while (!layout_object->IsSVGRoot())
     layout_object = layout_object->Parent();
   // Update the target node to point to the SVG root.
   target_node = layout_object->GetNode();
   DCHECK(!target_node ||
          (target_node->IsSVGElement() &&
           ToSVGElement(*target_node).IsOutermostSVGSVGElement()));
   return layout_object;
 }
 
+unsigned short WebPointerPropertiesButtonToButton(
+    const AtomicString& event_name,
+    WebPointerProperties::Button button) {
+  if (event_name == EventTypeNames::mousemove ||
+      event_name == EventTypeNames::mouseleave ||
+      event_name == EventTypeNames::mouseenter ||
+      event_name == EventTypeNames::mouseover ||
+      event_name == EventTypeNames::mouseout) {
+    return 0;
+  }
+  return static_cast<unsigned short>(button);
+}
+
 }  // namespace
 
 MouseEvent* MouseEvent::Create(ScriptState* script_state,
                                const AtomicString& type,
                                const MouseEventInit& initializer) {
   if (script_state && script_state->World().IsIsolatedWorld())
     UIEventWithKeyState::DidCreateEventInIsolatedWorld(
         initializer.ctrlKey(), initializer.altKey(), initializer.shiftKey(),
         initializer.metaKey());
   return new MouseEvent(type, initializer);
@@ skipping 75 matching lines @@
           detail,
           static_cast<WebInputEvent::Modifiers>(event.GetModifiers()),
           TimeTicks::FromSeconds(event.TimeStampSeconds()),
           abstract_view
               ? abstract_view->GetInputDeviceCapabilities()->FiresTouchEvents(
                     event.FromTouch())
               : nullptr),
       screen_location_(event.PositionInScreen().x, event.PositionInScreen().y),
       movement_delta_(FlooredIntPoint(event.MovementInRootFrame())),
       position_type_(PositionType::kPosition),
-      button_(static_cast<short>(event.button)),
+      button_(WebPointerPropertiesButtonToButton(event_type, event.button)),
       buttons_(WebInputEventModifiersToButtons(event.GetModifiers())),
       related_target_(related_target),
       synthetic_event_type_(event.FromTouch() ? kFromTouch
                                               : kRealOrIndistinguishable),
       region_(region) {
   IntPoint root_frame_coordinates =
       FlooredIntPoint(event.PositionInRootFrame());
   InitCoordinatesFromRootFrame(root_frame_coordinates.X(),
                                root_frame_coordinates.Y());
 }
@@ skipping 399 matching lines @@
 
 int MouseEvent::offsetY() {
   if (!HasPosition())
     return 0;
   if (!has_cached_relative_position_)
     ComputeRelativePosition();
   return std::round(offset_location_.Y());
 }
 
 }  // namespace blink