Update ui::PointerEvent to support mouse wheel and capture change events.

services/ui/ws/event_dispatcher.cc

Index: services/ui/ws/event_dispatcher.cc
diff --git a/services/ui/ws/event_dispatcher.cc b/services/ui/ws/event_dispatcher.cc
index 06c632338126f2ff3003a0152083913836d6ee5e..385f695aaf541ad70b276f63dc37e9e356eed4f3 100644
--- a/services/ui/ws/event_dispatcher.cc
+++ b/services/ui/ws/event_dispatcher.cc
@@ -53,13 +53,8 @@ bool IsLocationInNonclientArea(const ServerWindow* target,
 }
 
 uint32_t PointerId(const ui::LocatedEvent& event) {
-  if (event.IsPointerEvent())
-    return event.AsPointerEvent()->pointer_id();
-  if (event.IsMouseWheelEvent())
-    return ui::PointerEvent::kMousePointerId;
-
-  NOTREACHED();
-  return 0;
+  DCHECK(event.IsPointerEvent());
+  return event.AsPointerEvent()->pointer_id();
 }
 
 }  // namespace
@@ -287,7 +282,7 @@ void EventDispatcher::ProcessEvent(const ui::Event& event,
     return;
   }
 
-  if (event.IsPointerEvent() || event.IsMouseWheelEvent()) {
+  if (event.IsPointerEvent()) {
     ProcessLocatedEvent(*event.AsLocatedEvent());
     return;
   }
@@ -317,9 +312,10 @@ void EventDispatcher::ProcessKeyEvent(const ui::KeyEvent& event,
 }
 
 void EventDispatcher::ProcessLocatedEvent(const ui::LocatedEvent& event) {
-  DCHECK(event.IsPointerEvent() || event.IsMouseWheelEvent());
-  const bool is_mouse_event =
-      event.IsMousePointerEvent() || event.IsMouseWheelEvent();
+  // TODO(moshayedi): crbug.com/602859. Handle scroll events as
+  // they are once we have proper support for scroll events.
+  DCHECK(event.IsPointerEvent());
+  const bool is_mouse_event = event.IsMousePointerEvent();
 
   if (is_mouse_event) {
     mouse_pointer_last_location_ = event.root_location();