Add ability to bind a different InterfaceRegistry/InterfaceProvider to an incoming Connection.

services/shell/public/cpp/lib/interface_provider.cc

Index: services/shell/public/cpp/lib/interface_provider.cc
diff --git a/services/shell/public/cpp/lib/interface_provider.cc b/services/shell/public/cpp/lib/interface_provider.cc
index 6636444312992bb9b918ca02b81582c7edec688c..268c49a46bcf3b03752294258f6a232649f45683 100644
--- a/services/shell/public/cpp/lib/interface_provider.cc
+++ b/services/shell/public/cpp/lib/interface_provider.cc
@@ -6,12 +6,14 @@
 
 namespace shell {
 
-InterfaceProvider::InterfaceProvider(
-    mojom::InterfaceProviderPtr interface_provider)
-    : interface_provider_(std::move(interface_provider)),
-      weak_factory_(this) {}
+InterfaceProvider::InterfaceProvider() : weak_factory_(this) {}
 InterfaceProvider::~InterfaceProvider() {}
 
+void InterfaceProvider::Bind(mojom::InterfaceProviderPtr interface_provider) {
+  DCHECK(!interface_provider_.is_bound());
+  interface_provider_ = std::move(interface_provider);
+}
+
 void InterfaceProvider::SetConnectionLostClosure(
     const base::Closure& connection_lost_closure) {
   interface_provider_.set_connection_error_handler(connection_lost_closure);