Don't synthesize mousemove events if the mouse cursor is not on the widget

ui/views/widget/widget.cc

Index: ui/views/widget/widget.cc
diff --git a/ui/views/widget/widget.cc b/ui/views/widget/widget.cc
index 280969a84e5e7d0067d1f10378dec9d6d15061fb..513e9acd00c4eabaaa5fae744cf173043a269033 100644
--- a/ui/views/widget/widget.cc
+++ b/ui/views/widget/widget.cc
@@ -169,6 +169,7 @@ Widget::Widget()
       is_top_level_(false),
       native_widget_initialized_(false),
       native_widget_destroyed_(false),
+      hovered_(false),
       is_mouse_button_pressed_(false),
       ignore_capture_loss_(false),
       last_mouse_event_was_move_(false),
@@ -988,6 +989,9 @@ gfx::Rect Widget::GetWorkAreaBoundsInScreen() const {
 }
 
 void Widget::SynthesizeMouseMoveEvent() {
+  if (!hovered_)
+    return;
+
   last_mouse_event_was_move_ = false;
   ui::MouseEvent mouse_event(ui::ET_MOUSE_MOVED, last_mouse_event_position_,
                              last_mouse_event_position_, ui::EventTimeForNow(),
@@ -1230,7 +1234,12 @@ void Widget::OnMouseEvent(ui::MouseEvent* event) {
       }
       return;
 
+    case ui::ET_MOUSE_ENTERED:
+      hovered_ = true;
+      return;
+
     case ui::ET_MOUSE_EXITED:
+      hovered_ = false;
       last_mouse_event_was_move_ = false;
       if (root_view)
         root_view->OnMouseExited(*event);