ui: Pass display size by const reference in AddVirtualDisplay

ui/display/chromeos/display_configurator.cc

Index: ui/display/chromeos/display_configurator.cc
diff --git a/ui/display/chromeos/display_configurator.cc b/ui/display/chromeos/display_configurator.cc
index eb1c0a4a8c4fe385b3dca2a83ed0493d7287216b..23378703c26fcab9ac96ff61a868f4826852fc89 100644
--- a/ui/display/chromeos/display_configurator.cc
+++ b/ui/display/chromeos/display_configurator.cc
@@ -1116,7 +1116,7 @@ void DisplayConfigurator::NotifyPowerStateObservers() {
       Observer, observers_, OnPowerStateChanged(current_power_state_));
 }
 
-int64_t DisplayConfigurator::AddVirtualDisplay(gfx::Size display_size) {
+int64_t DisplayConfigurator::AddVirtualDisplay(const gfx::Size& display_size) {
   if (last_virtual_display_id_ == 0xff) {
     LOG(WARNING) << "Exceeded virtual display id limit";
     return display::Display::kInvalidDisplayID;