More graceful shutdown for ArcSession.

components/arc/test/fake_arc_session.cc

Index: components/arc/test/fake_arc_session.cc
diff --git a/components/arc/test/fake_arc_session.cc b/components/arc/test/fake_arc_session.cc
index 486068e7ebe633ebe3ebf909657ab74b70e40c34..5ebc1e04a0214e260cf8287c51f339647aebdf23 100644
--- a/components/arc/test/fake_arc_session.cc
+++ b/components/arc/test/fake_arc_session.cc
@@ -29,6 +29,10 @@ void FakeArcSession::Stop() {
   StopWithReason(ArcBridgeService::StopReason::SHUTDOWN);
 }
 
+void FakeArcSession::OnShutdown() {
+  StopWithReason(ArcBridgeService::StopReason::SHUTDOWN);
+}
+
 void FakeArcSession::StopWithReason(ArcBridgeService::StopReason reason) {
   for (auto& observer : observer_list_)
     observer.OnStopped(reason);