Revert of Clean up public interface of AttachmentBrokerUnprivileged.

content/child/child_thread_impl.cc

Index: content/child/child_thread_impl.cc
diff --git a/content/child/child_thread_impl.cc b/content/child/child_thread_impl.cc
index eb8ee2546d642734838ba4e1c249e9eb6317416e..5378463a0cdade74433293961bfc4ece5b7aea4b 100644
--- a/content/child/child_thread_impl.cc
+++ b/content/child/child_thread_impl.cc
@@ -367,7 +367,14 @@
   IPC::Logging::GetInstance();
 #endif
 
-  IPC::AttachmentBrokerUnprivileged::CreateBrokerIfNeeded();
+#if USE_ATTACHMENT_BROKER
+  // The only reason a global would already exist is if the thread is being run
+  // in the browser process because of a command line switch.
+  if (!IPC::AttachmentBroker::GetGlobal()) {
+    attachment_broker_.reset(
+        IPC::AttachmentBrokerUnprivileged::CreateBroker().release());
+  }
+#endif
 
   channel_ =
       IPC::SyncChannel::Create(this, ChildProcess::current()->io_task_runner(),
@@ -453,9 +460,8 @@
   }
 
   ConnectChannel(options.use_mojo_channel);
-  IPC::AttachmentBroker* global = IPC::AttachmentBroker::GetGlobal();
-  if (global && !global->IsPrivilegedBroker())
-    global->DesignateBrokerCommunicationChannel(channel_.get());
+  if (attachment_broker_)
+    attachment_broker_->DesignateBrokerCommunicationChannel(channel_.get());
 
   int connection_timeout = kConnectionTimeoutS;
   std::string connection_override =