Clean up public interface of AttachmentBrokerUnprivileged.

components/nacl/broker/nacl_broker_listener.cc

Index: components/nacl/broker/nacl_broker_listener.cc
diff --git a/components/nacl/broker/nacl_broker_listener.cc b/components/nacl/broker/nacl_broker_listener.cc
index cb104058082acf4b120eae0c92599ed514475122..78da409e0abe7e3fa0e3c0b3b40a1789e4e82731 100644
--- a/components/nacl/broker/nacl_broker_listener.cc
+++ b/components/nacl/broker/nacl_broker_listener.cc
@@ -32,8 +32,7 @@ void SendReply(IPC::Channel* channel, int32_t pid, bool result) {
 }  // namespace
 
 NaClBrokerListener::NaClBrokerListener() {
-  attachment_broker_.reset(
-      IPC::AttachmentBrokerUnprivileged::CreateBroker().release());
+  IPC::AttachmentBrokerUnprivileged::CreateBrokerIfNeeded();
 }
 
 NaClBrokerListener::~NaClBrokerListener() {
@@ -44,8 +43,9 @@ void NaClBrokerListener::Listen() {
       base::CommandLine::ForCurrentProcess()->GetSwitchValueASCII(
           switches::kProcessChannelID);
   channel_ = IPC::Channel::CreateClient(channel_name, this);
-  if (attachment_broker_.get())
-    attachment_broker_->DesignateBrokerCommunicationChannel(channel_.get());
+  IPC::AttachmentBroker* global = IPC::AttachmentBroker::GetGlobal();
+  if (global && !global->IsPrivilegedBroker())
+    global->DesignateBrokerCommunicationChannel(channel_.get());
   CHECK(channel_->Connect());
   base::MessageLoop::current()->Run();
 }