Use bootstrap subset ports to overcome Mach port mapping leaks and -10810 errors

chrome/app/chrome_main_mac.mm

Index: chrome/app/chrome_main_mac.mm
===================================================================
--- chrome/app/chrome_main_mac.mm	(revision 103028)
+++ chrome/app/chrome_main_mac.mm	(working copy)
@@ -5,6 +5,8 @@
 #include "chrome/app/chrome_main_mac.h"
 
 #import <Cocoa/Cocoa.h>
+#include <mach/mach.h>
+#include <servers/bootstrap.h>
 
 #include <string>
 
@@ -43,3 +45,45 @@
   NSBundle* base_bundle = chrome::OuterAppBundle();
   base::mac::SetBaseBundleID([[base_bundle bundleIdentifier] UTF8String]);
 }
+
+void SwitchToMachBootstrapSubsetPort() {
+  // Testing tip: use launchctl bstree (as root) to make sure that the
+  // subset port is created properly and that new mappings wind up added to
+  // the subset port.
+
+#ifndef NDEBUG
+  static bool once_only = false;
+  DCHECK(!once_only);
+  once_only = true;
+#endif
+
+  mach_port_t self_task = mach_task_self();
+
+  mach_port_t original_bootstrap_port;
+  kern_return_t kr = task_get_bootstrap_port(self_task,
+                                             &original_bootstrap_port);
+  if (kr != KERN_SUCCESS) {
+    LOG(ERROR) << "task_get_bootstrap_port: " << kr << " "
+               << mach_error_string(kr);
+    return;
+  }
+
+  mach_port_t bootstrap_subset_port;
+  kr = bootstrap_subset(original_bootstrap_port,
+                        self_task,
+                        &bootstrap_subset_port);
+  if (kr != BOOTSTRAP_SUCCESS) {
+    LOG(ERROR) << "bootstrap_subset: " << kr << " " << bootstrap_strerror(kr);
+    return;
+  }
+
+  kr = task_set_bootstrap_port(self_task, bootstrap_subset_port);
+  if (kr != KERN_SUCCESS) {
+    LOG(ERROR) << "task_set_bootstrap_port: " << kr << " "
+               << mach_error_string(kr);
+    return;
+  }
+
+  // Users of the bootstrap port often access it through this global variable.
+  bootstrap_port = bootstrap_subset_port;
+}