Revert of Clean up public interface of AttachmentBrokerUnprivileged.

remoting/host/desktop_process.cc

Index: remoting/host/desktop_process.cc
diff --git a/remoting/host/desktop_process.cc b/remoting/host/desktop_process.cc
index e59b8a58be8e2d5ee6f864ad8783e5bc268dc0a7..b0afa8e16d072444577e019908b732179b927839 100644
--- a/remoting/host/desktop_process.cc
+++ b/remoting/host/desktop_process.cc
@@ -82,9 +82,6 @@
 
 void DesktopProcess::OnChannelError() {
   // Shutdown the desktop process.
-  IPC::AttachmentBroker* broker = IPC::AttachmentBroker::GetGlobal();
-  if (broker && !broker->IsPrivilegedBroker())
-    broker->DeregisterBrokerCommunicationChannel(daemon_channel_.get());
   daemon_channel_.reset();
   if (desktop_agent_.get()) {
     desktop_agent_->Stop();
@@ -144,10 +141,14 @@
       IPC::ChannelProxy::Create(daemon_channel_name_, IPC::Channel::MODE_CLIENT,
                                 this, io_task_runner.get());
 
-  IPC::AttachmentBrokerUnprivileged::CreateBrokerIfNeeded();
-  IPC::AttachmentBroker* broker = IPC::AttachmentBroker::GetGlobal();
-  if (broker && !broker->IsPrivilegedBroker())
-    broker->RegisterBrokerCommunicationChannel(daemon_channel_.get());
+  // Attachment broker may be already created in tests.
+  if (!IPC::AttachmentBroker::GetGlobal())
+    attachment_broker_ = IPC::AttachmentBrokerUnprivileged::CreateBroker();
+
+  if (attachment_broker_) {
+    attachment_broker_->DesignateBrokerCommunicationChannel(
+        daemon_channel_.get());
+  }
 
   // Pass |desktop_pipe| to the daemon.
   daemon_channel_->Send(