Mojo C++ bindings: remove usage of AssociatedGroup from ipc/

ipc/ipc_sync_message_filter.cc

Index: ipc/ipc_sync_message_filter.cc
diff --git a/ipc/ipc_sync_message_filter.cc b/ipc/ipc_sync_message_filter.cc
index 77c6a3a0c77ddff52615b35096fa2a5a104e2151..ffccff3d50889271ac0b4c0926b10f62eb9e4ea8 100644
--- a/ipc/ipc_sync_message_filter.cc
+++ b/ipc/ipc_sync_message_filter.cc
@@ -172,10 +172,6 @@ void SyncMessageFilter::OnFilterAdded(Channel* channel) {
   {
     base::AutoLock auto_lock(lock_);
     channel_ = channel;
-    Channel::AssociatedInterfaceSupport* support =
-        channel_->GetAssociatedInterfaceSupport();
-    if (support)
-      channel_associated_group_ = *support->GetAssociatedGroup();
 
     io_task_runner_ = base::ThreadTaskRunnerHandle::Get();
     shutdown_watcher_.StartWatching(