views/mus: Have explicit ownership of views::WindowManagerConnection.

mash/browser/browser.cc

Index: mash/browser/browser.cc
diff --git a/mash/browser/browser.cc b/mash/browser/browser.cc
index 0938f0278d93b333eb7aba940c08317e3dd315c7..418cd825a46ea256e938c193bc1e20da09c9002b 100644
--- a/mash/browser/browser.cc
+++ b/mash/browser/browser.cc
@@ -334,7 +334,8 @@ void Browser::Initialize(shell::Connector* connector,
   tracing_.Initialize(connector, identity.name());
 
   aura_init_.reset(new views::AuraInit(connector, "views_mus_resources.pak"));
-  views::WindowManagerConnection::Create(connector, identity);
+  window_manager_connection_ =
+      views::WindowManagerConnection::Create(connector, identity);
 }
 
 bool Browser::AcceptConnection(shell::Connection* connection) {