Update from https://crrev.com/316786

sandbox/linux/services/proc_util.h

Index: sandbox/linux/services/proc_util.h
diff --git a/sandbox/linux/services/proc_util.h b/sandbox/linux/services/proc_util.h
index 9d9bb2ea39936e021a324e994f302fcec283030e..74388f8036c61e235e297b2e22473892d3b18d4c 100644
--- a/sandbox/linux/services/proc_util.h
+++ b/sandbox/linux/services/proc_util.h
@@ -5,6 +5,7 @@
 #ifndef SANDBOX_LINUX_SERVICES_PROC_UTIL_H_
 #define SANDBOX_LINUX_SERVICES_PROC_UTIL_H_
 
+#include "base/files/scoped_file.h"
 #include "base/macros.h"
 #include "sandbox/sandbox_export.h"
 
@@ -31,6 +32,9 @@ class SANDBOX_EXPORT ProcUtil {
   // false.
   static bool HasOpenDirectory(int proc_fd);
 
+  // Open /proc/self/task/ or crash if it cannot.
+  static base::ScopedFD OpenProcSelfTask();
+
  private:
   DISALLOW_IMPLICIT_CONSTRUCTORS(ProcUtil);
 };