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

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

Index: mojo/public/cpp/bindings/lib/binding_state.h
diff --git a/mojo/public/cpp/bindings/lib/binding_state.h b/mojo/public/cpp/bindings/lib/binding_state.h
index 0591cb4f8e138d86feb336dbd66aa5b1e5251e34..dec6bd47436fa9e74a103529e3f778e47895c0f4 100644
--- a/mojo/public/cpp/bindings/lib/binding_state.h
+++ b/mojo/public/cpp/bindings/lib/binding_state.h
@@ -180,7 +180,6 @@
 
  protected:
   void BindInternal(ScopedMessagePipeHandle handle,
-                    MultiplexRouter::Config config,
                     scoped_refptr<base::SingleThreadTaskRunner> runner,
                     const char* interface_name,
                     std::unique_ptr<MessageReceiver> request_validator,
@@ -206,10 +205,7 @@
   void Bind(ScopedMessagePipeHandle handle,
             scoped_refptr<base::SingleThreadTaskRunner> runner) {
     MultiplexedBindingState::BindInternal(
-        std::move(handle),
-        Interface::PassesAssociatedKinds_ ? MultiplexRouter::MULTI_INTERFACE
-                                          : MultiplexRouter::SINGLE_INTERFACE,
-        runner, Interface::Name_,
+        std::move(handle), runner, Interface::Name_,
         base::MakeUnique<typename Interface::RequestValidator_>(),
         Interface::HasSyncMethods_, &stub_, Interface::Version_);
     stub_.serialization_context()->group_controller = router_;