Random fixes for mash bridge classes

components/mus/public/cpp/lib/window_tree_client_impl.cc

Index: components/mus/public/cpp/lib/window_tree_client_impl.cc
diff --git a/components/mus/public/cpp/lib/window_tree_client_impl.cc b/components/mus/public/cpp/lib/window_tree_client_impl.cc
index dc439ce190eba16798135df213c721a1aab28424..6f2b2936231f6d33ff655c07fea5a8343af999a3 100644
--- a/components/mus/public/cpp/lib/window_tree_client_impl.cc
+++ b/components/mus/public/cpp/lib/window_tree_client_impl.cc
@@ -166,6 +166,9 @@ WindowTreeClientImpl::~WindowTreeClientImpl() {
   while (!tracker.windows().empty())
     delete tracker.windows().front();
 
+  FOR_EACH_OBSERVER(WindowTreeConnectionObserver, observers_,
+                    OnWillDestroyConnection(this));
+
   delegate_->OnConnectionLost(this);
 }