Mojo C++ bindings: reduce references to AssociatedGroupController.

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

 // Copyright 2015 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef MOJO_PUBLIC_CPP_BINDINGS_LIB_BINDING_STATE_H_
 #define MOJO_PUBLIC_CPP_BINDINGS_LIB_BINDING_STATE_H_
 
 #include <memory>
 #include <string>
 #include <utility>
@@ skipping 198 matching lines @@
 
   ~BindingState() { Close(); }
 
   void Bind(ScopedMessagePipeHandle handle,
             scoped_refptr<base::SingleThreadTaskRunner> runner) {
     MultiplexedBindingState::BindInternal(
         std::move(handle), runner, Interface::Name_,
         base::MakeUnique<typename Interface::RequestValidator_>(),
         Interface::PassesAssociatedKinds_, Interface::HasSyncMethods_, &stub_,
         Interface::Version_);
-    stub_.serialization_context()->group_controller = router_;
+    if (Interface::PassesAssociatedKinds_)
+      stub_.serialization_context()->group_controller = router_;
   }
 
   InterfaceRequest<Interface> Unbind() {
     endpoint_client_.reset();
     InterfaceRequest<Interface> request =
         MakeRequest<Interface>(router_->PassMessagePipe());
     router_ = nullptr;
     return request;
   }
 
   Interface* impl() { return ImplRefTraits::GetRawPointer(&stub_.sink()); }
 
  private:
   typename Interface::template Stub_<ImplRefTraits> stub_;
 
   DISALLOW_COPY_AND_ASSIGN(BindingState);
 };
 
 }  // namesapce internal
 }  // namespace mojo
 
 #endif  // MOJO_PUBLIC_CPP_BINDINGS_LIB_BINDING_STATE_H_