Don't center screen magnification on empty focus rectangle

ash/magnifier/magnification_controller.cc

Index: ash/magnifier/magnification_controller.cc
diff --git a/ash/magnifier/magnification_controller.cc b/ash/magnifier/magnification_controller.cc
index e4c5b8ee90b3a3d9a19f3fa8691338d23bb1d729..d0ec016cee9c646c61ff51072c9539a22c4f24d1 100644
--- a/ash/magnifier/magnification_controller.cc
+++ b/ash/magnifier/magnification_controller.cc
@@ -435,6 +435,10 @@ void MagnificationControllerImpl::HandleFocusedNodeChanged(
   if (is_editable_node)
     return;
 
+  // Nothing to recenter on.
+  if (node_bounds_in_screen.IsEmpty())
+    return;
+
   gfx::Rect node_bounds_in_root =
       ScreenUtil::ConvertRectFromScreen(root_window_, node_bounds_in_screen);
   if (GetViewportRect().Contains(node_bounds_in_root))