Clean up public interface of AttachmentBrokerUnprivileged.

remoting/host/remoting_me2me_host.cc

Index: remoting/host/remoting_me2me_host.cc
diff --git a/remoting/host/remoting_me2me_host.cc b/remoting/host/remoting_me2me_host.cc
index 589c24b29e6b62132ed507ff98ac7f79641f0167..b1d136f9a03372349c5861d0b7e19ea0198505ab 100644
--- a/remoting/host/remoting_me2me_host.cc
+++ b/remoting/host/remoting_me2me_host.cc
@@ -458,9 +458,6 @@ class HostProcess : public ConfigWatcher::Delegate,
   // Accessed on the UI thread.
   scoped_ptr<IPC::ChannelProxy> daemon_channel_;
 
-  // AttachmentBroker for |daemon_channel_|.
-  scoped_ptr<IPC::AttachmentBrokerUnprivileged> attachment_broker_;
-
   // Owned as |desktop_environment_factory_|.
   DesktopSessionConnector* desktop_session_connector_ = nullptr;
 #endif  // defined(REMOTING_MULTI_PROCESS)
@@ -542,11 +539,10 @@ bool HostProcess::InitWithCommandLine(const base::CommandLine* cmd_line) {
                                               this,
                                               context_->network_task_runner());
 
-  attachment_broker_ = IPC::AttachmentBrokerUnprivileged::CreateBroker();
-  if (attachment_broker_) {
-    attachment_broker_->DesignateBrokerCommunicationChannel(
-        daemon_channel_.get());
-  }
+  IPC::AttachmentBrokerUnprivileged::CreateBrokerIfNeeded();
+  IPC::AttachmentBroker* global = IPC::AttachmentBroker::GetGlobal();
+  if (global && !global->IsPrivilegedBroker())
+    global->DesignateBrokerCommunicationChannel(daemon_channel_.get());
 
 #else  // !defined(REMOTING_MULTI_PROCESS)
   if (cmd_line->HasSwitch(kHostConfigSwitchName)) {