Mojo C++ Bindings: Extract AssociatedGroupController from MultiplexRouter

mojo/public/cpp/bindings/lib/interface_id.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_INTERFACE_ID_H_
-#define MOJO_PUBLIC_CPP_BINDINGS_LIB_INTERFACE_ID_H_
-
-#include <stdint.h>
-
-namespace mojo {
-namespace internal {
-
-// The size of the type matters because it is directly used in messages.
-using InterfaceId = uint32_t;
-
-// IDs of associated interface can be generated at both sides of the message
-// pipe. In order to avoid collision, the highest bit is used as namespace bit:
-// at the side where the client-side of the master interface lives, IDs are
-// generated with the namespace bit set to 1; at the opposite side IDs are
-// generated with the namespace bit set to 0.
-const uint32_t kInterfaceIdNamespaceMask = 0x80000000;
-
-const InterfaceId kMasterInterfaceId = 0x00000000;
-const InterfaceId kInvalidInterfaceId = 0xFFFFFFFF;
-
-inline bool IsMasterInterfaceId(InterfaceId id) {
-  return id == kMasterInterfaceId;
-}
-
-inline bool IsValidInterfaceId(InterfaceId id) {
-  return id != kInvalidInterfaceId;
-}
-
-}  // namespace internal
-}  // namespace mojo
-
-#endif  // MOJO_PUBLIC_CPP_BINDINGS_LIB_INTERFACE_ID_H_