[WIP] ScreenManager: Add an external window mode

services/ui/display/screen_manager_stub.cc

Index: services/ui/display/screen_manager_stub.cc
diff --git a/services/ui/display/screen_manager_stub.cc b/services/ui/display/screen_manager_stub.cc
index c664c8452bc72ff855bc84ec0f82d9eb581f6f4f..bae8379460933b38d69a734f00b9002997e03613 100644
--- a/services/ui/display/screen_manager_stub.cc
+++ b/services/ui/display/screen_manager_stub.cc
@@ -54,7 +54,8 @@ void ScreenManagerStub::FixedSizeScreenConfiguration() {
 void ScreenManagerStub::AddInterfaces(
     service_manager::InterfaceRegistry* registry) {}
 
-void ScreenManagerStub::Init(ScreenManagerDelegate* delegate) {
+void ScreenManagerStub::Init(ScreenManagerDelegate* delegate,
+                             WindowMode window_mode) {
   DCHECK(delegate);
   delegate_ = delegate;
   display_metrics_ = DefaultViewportMetrics();