cc: Fix bug where tabs have the wrong scale factor

cc/trees/layer_tree_impl.cc

Index: cc/trees/layer_tree_impl.cc
diff --git a/cc/trees/layer_tree_impl.cc b/cc/trees/layer_tree_impl.cc
index d44aa67fefea548b7336ed830cc9d27c9471fd60..bfaead30c0dfd13f3ce8dfe32d314120bad1f636 100644
--- a/cc/trees/layer_tree_impl.cc
+++ b/cc/trees/layer_tree_impl.cc
@@ -599,6 +599,7 @@ void LayerTreeImpl::SetDeviceScaleFactor(float device_scale_factor) {
     return;
   device_scale_factor_ = device_scale_factor;
 
+  set_needs_update_draw_properties();
   if (IsActiveTree())
     layer_tree_host_impl_->SetFullRootLayerDamage();
 }