Cleanup remaining class/struct fwd declarations

mojo/public/cpp/bindings/lib/multiplex_router.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_MULTIPLEX_ROUTER_H_
 #define MOJO_PUBLIC_CPP_BINDINGS_LIB_MULTIPLEX_ROUTER_H_
 
 #include <stdint.h>
 
 #include <deque>
@@ skipping 19 matching lines @@
 #include "mojo/public/cpp/bindings/pipe_control_message_handler_delegate.h"
 #include "mojo/public/cpp/bindings/pipe_control_message_proxy.h"
 #include "mojo/public/cpp/bindings/scoped_interface_endpoint_handle.h"
 
 namespace base {
 class SingleThreadTaskRunner;
 }
 
 namespace mojo {
 
-class AssociatedGroup;
-
 namespace internal {
 
 // MultiplexRouter supports routing messages for multiple interfaces over a
 // single message pipe.
 //
 // It is created on the thread where the master interface of the message pipe
 // lives. Although it is ref-counted, it is guarateed to be destructed on the
 // same thread.
 // Some public methods are only allowed to be called on the creating thread;
 // while the others are safe to call from any threads. Please see the method
@@ skipping 210 matching lines @@
 
   bool testing_mode_;
 
   DISALLOW_COPY_AND_ASSIGN(MultiplexRouter);
 };
 
 }  // namespace internal
 }  // namespace mojo
 
 #endif  // MOJO_PUBLIC_CPP_BINDINGS_LIB_MULTIPLEX_ROUTER_H_