Revert of Mojo C++ bindings: always use MultiplexRouter with InterfacePtr/Binding.

mojo/public/cpp/bindings/lib/binding_state.cc

Index: mojo/public/cpp/bindings/lib/binding_state.cc
diff --git a/mojo/public/cpp/bindings/lib/binding_state.cc b/mojo/public/cpp/bindings/lib/binding_state.cc
index 0b0c553c8ae15fdfdb3d130195876f987a1e90be..c9462745906f0493fdc08f8f8f22f6939a93a2c1 100644
--- a/mojo/public/cpp/bindings/lib/binding_state.cc
+++ b/mojo/public/cpp/bindings/lib/binding_state.cc
@@ -138,7 +138,6 @@
 
 void MultiplexedBindingState::BindInternal(
     ScopedMessagePipeHandle handle,
-    MultiplexRouter::Config config,
     scoped_refptr<base::SingleThreadTaskRunner> runner,
     const char* interface_name,
     std::unique_ptr<MessageReceiver> request_validator,
@@ -147,7 +146,8 @@
     uint32_t interface_version) {
   DCHECK(!router_);
 
-  router_ = new MultiplexRouter(std::move(handle), config, false, runner);
+  router_ = new MultiplexRouter(
+      std::move(handle), MultiplexRouter::MULTI_INTERFACE, false, runner);
   router_->SetMasterInterfaceName(interface_name);
 
   endpoint_client_.reset(new InterfaceEndpointClient(