chromeos: Makes mushrome use simplified display management

services/ui/display/screen_manager_forwarding.cc

Index: services/ui/display/screen_manager_forwarding.cc
diff --git a/services/ui/display/screen_manager_forwarding.cc b/services/ui/display/screen_manager_forwarding.cc
index 9ea90983fabfd12083f02a5cb54ca505504791ea..2ee16f2a1afd82678b206bc593e0c2bb805b1266 100644
--- a/services/ui/display/screen_manager_forwarding.cc
+++ b/services/ui/display/screen_manager_forwarding.cc
@@ -37,11 +37,14 @@ const DisplayMode* GetCorrespondingMode(const DisplaySnapshot& snapshot,
 }  // namespace
 
 ScreenManagerForwarding::ScreenManagerForwarding()
-    : screen_(base::MakeUnique<display::ScreenBase>()), binding_(this) {}
+    : screen_(base::MakeUnique<display::ScreenBase>()), binding_(this) {
+  Screen::SetScreenInstance(screen_.get());
+}
 
 ScreenManagerForwarding::~ScreenManagerForwarding() {
   if (native_display_delegate_)
     native_display_delegate_->RemoveObserver(this);
+  Screen::SetScreenInstance(nullptr);
 }
 
 void ScreenManagerForwarding::AddInterfaces(