Fix destruction order in mus_demo

services/ui/demo/mus_demo.cc

Index: services/ui/demo/mus_demo.cc
diff --git a/services/ui/demo/mus_demo.cc b/services/ui/demo/mus_demo.cc
index 7afba5693af4cae100e7e13c0f09af916494b989..6a337c03652f64ef0b09d53c2738023b6fc76eff 100644
--- a/services/ui/demo/mus_demo.cc
+++ b/services/ui/demo/mus_demo.cc
@@ -24,6 +24,12 @@ MusDemo::MusDemo() {}
 
 MusDemo::~MusDemo() {
   display::Screen::SetScreenInstance(nullptr);
+  // Destruction order is important here:
+  // WindowTreeClient must be destroyed before Env and WMState, otherwise
+  // segfault occurs as long as WindowTreeClient uses these singletons in it's
+  // dtor.

[kylechar, 2017/03/21 12:44:45]

s/dtor/destructor

+  window_tree_data_list_.clear();
+  window_tree_client_.reset();

[fwang, 2017/03/21 07:12:02]

Two points:
1) I think you should explain that windows (from window_tree_data_list_) must be
destroyed before the window tree client.
2) Maybe you can explicitly destroy Env and WMState to make things clearer.

[msisov, 2017/03/21 07:16:55]

Done.

 }
 
 void MusDemo::AddPrimaryDisplay(const display::Display& display) {