Mark the ET_MOUSE_MOVED created from a pointer grab as synthesized.

ui/events/x/events_x_unittest.cc

Index: ui/events/x/events_x_unittest.cc
diff --git a/ui/events/x/events_x_unittest.cc b/ui/events/x/events_x_unittest.cc
index cf62b2b75a650c2a7d3b0e833080ac303163c1b2..a7082e602592bd9337098010fab4912691bbc556 100644
--- a/ui/events/x/events_x_unittest.cc
+++ b/ui/events/x/events_x_unittest.cc
@@ -189,6 +189,7 @@ TEST_F(EventsXTest, EnterLeaveEvent) {
   // the way views handle mouse enter. See comments for EnterNotify case in
   // ui::EventTypeFromNative for more details.
   EXPECT_EQ(ui::ET_MOUSE_MOVED, ui::EventTypeFromNative(&event));
+  EXPECT_TRUE(ui::EventFlagsFromNative(&event) & ui::EF_IS_SYNTHESIZED);
   EXPECT_EQ(
       "10,20",
       gfx::ToFlooredPoint(ui::EventLocationFromNative(&event)).ToString());