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

content/browser/renderer_host/input/web_input_event_builders_mac.mm

Index: content/browser/renderer_host/input/web_input_event_builders_mac.mm
diff --git a/content/browser/renderer_host/input/web_input_event_builders_mac.mm b/content/browser/renderer_host/input/web_input_event_builders_mac.mm
index 2e8ea376b856638125284351bfa9cf527ce25316..aee06487ea8bd3c4c71949616e586938298a031f 100644
--- a/content/browser/renderer_host/input/web_input_event_builders_mac.mm
+++ b/content/browser/renderer_host/input/web_input_event_builders_mac.mm
@@ -663,7 +663,10 @@ blink::WebKeyboardEvent WebKeyboardEventBuilder::Build(NSEvent* event) {
 
 // WebMouseEvent --------------------------------------------------------------
 
-blink::WebMouseEvent WebMouseEventBuilder::Build(NSEvent* event, NSView* view) {
+blink::WebMouseEvent WebMouseEventBuilder::Build(
+    NSEvent* event,
+    NSView* view,
+    blink::WebPointerProperties::PointerType pointerType) {
   blink::WebMouseEvent result;
 
   result.clickCount = 0;
@@ -729,6 +732,20 @@ blink::WebMouseEvent WebMouseEventBuilder::Build(NSEvent* event, NSView* view) {
 
   result.timeStampSeconds = [event timestamp];
 
+  NSEventSubtype subtype = NSMouseEventSubtype;
+  if ([event type] != NSMouseExited && [event type] != NSMouseEntered)
+    subtype = [event subtype];
+  // For the mouse events and the touchpad events, the pointer type is mouse.
+  // For all tablet events, the pointer type will be just pen.
+  if (subtype == NSTabletPointEventSubtype ||
+      subtype == NSTabletProximityEventSubtype) {
+    result.pointerType = blink::WebPointerProperties::PointerType::Pen;
+    return result;
+  }
+
+  // Set the pointerType based on if the pointing device enters or leaves the
+  // proximity of its tablet.
+  result.pointerType = pointerType;
   return result;
 }