mus: Allow SetModal to fail gracefully

components/mus/public/cpp/lib/in_flight_change.h

Index: components/mus/public/cpp/lib/in_flight_change.h
diff --git a/components/mus/public/cpp/lib/in_flight_change.h b/components/mus/public/cpp/lib/in_flight_change.h
index f848ab3b9fe4a2f1e780fc88b09454a248b1e9d5..d38e2d1062f693e2137fe436abfa32177054704c 100644
--- a/components/mus/public/cpp/lib/in_flight_change.h
+++ b/components/mus/public/cpp/lib/in_flight_change.h
@@ -264,6 +264,18 @@ class InFlightVisibleChange : public InFlightChange {
   DISALLOW_COPY_AND_ASSIGN(InFlightVisibleChange);
 };
 
+class InFlightSetModalChange : public InFlightChange {
+ public:
+  InFlightSetModalChange(Window* window);

[sky, 2016/03/17 22:59:42]

explicit, and don't have the compiler generate destructor.

[mohsen, 2016/03/17 23:51:30]

Done. Also added destructor for InFlightVisibleChange.

+
+  // InFlightChange:
+  void SetRevertValueFrom(const InFlightChange& change) override;
+  void Revert() override;
+
+ private:
+  DISALLOW_COPY_AND_ASSIGN(InFlightSetModalChange);
+};
+
 }  // namespace mus
 
 #endif  // COMPONENTS_MUS_PUBLIC_CPP_LIB_IN_FLIGHT_CHANGE_H_