Mark the ET_MOUSE_MOVED created from a pointer grab as synthesized.

ui/platform_window/x11/x11_window.cc

Index: ui/platform_window/x11/x11_window.cc
diff --git a/ui/platform_window/x11/x11_window.cc b/ui/platform_window/x11/x11_window.cc
index 64bd7a8f1ae3a566a5e1d5c89299915026ff8d7b..9630d3f740bb56a7e84501638127ce659f17591d 100644
--- a/ui/platform_window/x11/x11_window.cc
+++ b/ui/platform_window/x11/x11_window.cc
@@ -87,11 +87,8 @@ uint32_t X11Window::DispatchEvent(const PlatformEvent& event) {
   XEvent* xev = event;
   switch (xev->type) {
     case EnterNotify: {
-      // EnterNotify creates ET_MOUSE_MOVED. Mark as synthesized as this is
-      // not real mouse move event.
       MouseEvent mouse_event(xev);
       CHECK_EQ(ET_MOUSE_MOVED, mouse_event.type());
-      mouse_event.set_flags(mouse_event.flags() | EF_IS_SYNTHESIZED);
       delegate()->DispatchEvent(&mouse_event);
       break;
     }