Replace ApplicationImpl::CreateApplicationConnector() with a standalone helper function.

mojo/public/cpp/application/connect.h

Index: mojo/public/cpp/application/connect.h
diff --git a/mojo/public/cpp/application/connect.h b/mojo/public/cpp/application/connect.h
index e9c0793aca808dc1ae9a214855e45e712539646b..946ca7df57b84b27ffc61b8d0c05f9bedc0bdd0f 100644
--- a/mojo/public/cpp/application/connect.h
+++ b/mojo/public/cpp/application/connect.h
@@ -7,6 +7,7 @@
 #ifndef MOJO_PUBLIC_CPP_APPLICATION_CONNECT_H_
 #define MOJO_PUBLIC_CPP_APPLICATION_CONNECT_H_
 
+#include "mojo/public/cpp/bindings/interface_handle.h"
 #include "mojo/public/cpp/bindings/interface_request.h"
 #include "mojo/public/interfaces/application/application_connector.mojom.h"
 #include "mojo/public/interfaces/application/service_provider.mojom.h"
@@ -58,6 +59,10 @@ inline void ConnectToService(ApplicationConnector* application_connector,
   ConnectToService(service_provider.get(), request.Pass());
 }
 
+// Helper for getting an |InterfaceHandle<ApplicationConnector>| (which can be
+// passed to any thread) from the shell.
+InterfaceHandle<ApplicationConnector> CreateApplicationConnector(Shell* shell);
+
 }  // namespace mojo
 
 #endif  // MOJO_PUBLIC_CPP_APPLICATION_CONNECT_H_