macOS V2 GPU Sandbox: Diagnose mach service hang.

This is a temporary CL to locate and diagnose a mach service acccess
that is hanging.

Bug: 871280
Change-Id: I8ef068baa2f6f4b6eb3dd7a15671dffc399db2dc
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1599251
Commit-Queue: Greg Kerr <kerrnel@chromium.org>
Commit-Queue: Robert Sesek <rsesek@chromium.org>
Auto-Submit: Greg Kerr <kerrnel@chromium.org>
Reviewed-by: Robert Sesek <rsesek@chromium.org>
Cr-Commit-Position: refs/heads/master@{#657377}

services/service_manager/sandbox/mac/gpu_v2.sb

@@ -86,6 +86,16 @@
   (subpath "/System/Library/Video/Plug-Ins")
 )
 
-; A temporary test to diagnose a hang.
+; A temporary test to diagnose a hang - crbug.com/871280
 (if (string=? (param bundle-id) "com.google.Chrome.canary")
-  (allow mach-lookup))
+  (begin
+    (deny (with no-log) mach-lookup
+      (global-name "com.apple.cfprefsd.daemon")
+      (global-name "com.apple.GameController.gamecontrollerd")
+      (global-name "com.apple.bsd.dirhelper")
+      (global-name "com.apple.system.opendirectoryd.membership")
+      (global-name "com.apple.powerlog.plxpclogger.xpc")
+      (global-name "com.apple.PowerManagement.control")
+    )
+    (deny mach-lookup (with send-signal SIGFPE)))
+)