Unify mustash display closing code paths.

services/ui/display/platform_screen_stub.cc

Index: services/ui/display/platform_screen_stub.cc
diff --git a/services/ui/display/platform_screen_stub.cc b/services/ui/display/platform_screen_stub.cc
index 4b133dfbfbd2ba087a9a3ca9d3c9dc2fd5764dd1..6a23e25b8547de2c6a109d5de46f68552c12d7db 100644
--- a/services/ui/display/platform_screen_stub.cc
+++ b/services/ui/display/platform_screen_stub.cc
@@ -43,6 +43,14 @@ void PlatformScreenStub::Init(PlatformScreenDelegate* delegate) {
                             weak_ptr_factory_.GetWeakPtr()));
 }
 
+void PlatformScreenStub::RequestCloseDisplay(int64_t display_id) {
+  if (display_id == kDisplayId) {
+    base::ThreadTaskRunnerHandle::Get()->PostTask(
+        FROM_HERE, base::Bind(&PlatformScreenDelegate::OnDisplayRemoved,
+                              base::Unretained(delegate_), display_id));
+  }
+}
+
 int64_t PlatformScreenStub::GetPrimaryDisplayId() const {
   return kDisplayId;
 }