Identity the mouse pointer type from low-level events for Mac

content/browser/renderer_host/input/web_input_event_builders_mac.mm

 // Copyright 2015 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.
 
 /*
  * Copyright (C) 2004, 2006, 2007 Apple Inc. All rights reserved.
  * Copyright (C) 2006-2009 Google Inc.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
@@ skipping 650 matching lines @@
   return result;
 }
 
 // WebMouseEvent --------------------------------------------------------------
 
 blink::WebMouseEvent WebMouseEventBuilder::Build(NSEvent* event, NSView* view) {
   blink::WebMouseEvent result;
 
   result.clickCount = 0;
 
-  switch ([event type]) {
+  NSEventType type = [event type];
+  switch (type) {
     case NSMouseExited:
       result.type = blink::WebInputEvent::MouseLeave;
       result.button = blink::WebMouseEvent::ButtonNone;
       break;
     case NSLeftMouseDown:
       result.type = blink::WebInputEvent::MouseDown;
       result.clickCount = [event clickCount];
       result.button = blink::WebMouseEvent::ButtonLeft;
       break;
     case NSOtherMouseDown:
@@ skipping 40 matching lines @@
     default:
       NOTIMPLEMENTED();
   }
 
   SetWebEventLocationFromEventInView(&result, event, view);
 
   result.modifiers = ModifiersFromEvent(event);
 
   result.timeStampSeconds = [event timestamp];
 
+  // For NSMouseExited and NSMouseEntered, they do not have a subtype. Styluses
+  // and mouses share the same cursor, so we will set their pointerType as
+  // Unknown for now.
+  if (type == NSMouseExited || type == NSMouseEntered) {
+    result.pointerType = blink::WebPointerProperties::PointerType::Unknown;
+    return result;
+  }
+
+  // For other mouse events and touchpad events, the pointer type is mouse.
+  // For all other tablet events, the pointer type will be just pen.
+  NSEventSubtype subtype = [event subtype];
+  if (subtype == NSTabletPointEventSubtype ||
+      subtype == NSTabletProximityEventSubtype) {
+    result.pointerType = blink::WebPointerProperties::PointerType::Pen;
+  } else {
+    result.pointerType = blink::WebPointerProperties::PointerType::Mouse;
+  }
+  result.id = [event deviceID];
+  result.force = [event pressure];
   return result;
 }
 
 // WebMouseWheelEvent ---------------------------------------------------------
 
 blink::WebMouseWheelEvent WebMouseWheelEventBuilder::Build(
     NSEvent* event,
     NSView* view,
     bool can_rubberband_left,
     bool can_rubberband_right) {
@@ skipping 189 matching lines @@
       break;
     default:
       NOTIMPLEMENTED();
       result.type = blink::WebInputEvent::Undefined;
   }
 
   return result;
 }
 
 }  // namespace content