ipc: Use a global for the process's attachment broker.

content/public/common/child_process_host.h

Index: content/public/common/child_process_host.h
diff --git a/content/public/common/child_process_host.h b/content/public/common/child_process_host.h
index 0d4815a21dde3280b119e80e31ca75d2e92b2bbf..afeed7bfb6c16434573b87fbd4b962d6f3cd60e5 100644
--- a/content/public/common/child_process_host.h
+++ b/content/public/common/child_process_host.h
@@ -89,10 +89,6 @@ class CONTENT_EXPORT ChildProcessHost : public IPC::Sender {
   // On failure, returns an empty FilePath.
   static base::FilePath GetChildPath(int flags);
 
-  // Returns an AttachmentBroker used to broker attachments of IPC messages to
-  // child processes.
-  static IPC::AttachmentBrokerPrivileged* GetAttachmentBroker();
-
   // Send the shutdown message to the child process.
   // Does not check with the delegate's CanShutdown.
   virtual void ForceShutdown() = 0;