Extract CreateInitProcessReaper() from the Zygote.

sandbox/linux/suid/client/setuid_sandbox_client.cc

Index: sandbox/linux/suid/client/setuid_sandbox_client.cc
diff --git a/sandbox/linux/suid/client/setuid_sandbox_client.cc b/sandbox/linux/suid/client/setuid_sandbox_client.cc
index 34231d47a1b46c21bf8e45687b51f87ae4df5e1f..740823a8b36d641822b25f38cdd7ab6e48fcdbad 100644
--- a/sandbox/linux/suid/client/setuid_sandbox_client.cc
+++ b/sandbox/linux/suid/client/setuid_sandbox_client.cc
@@ -12,6 +12,7 @@
 #include "base/posix/eintr_wrapper.h"
 #include "base/strings/string_number_conversions.h"
 
+#include "sandbox/linux/services/init_process_reaper.h"
 #include "sandbox/linux/suid/common/sandbox.h"
 #include "sandbox/linux/suid/common/suid_unsafe_environment_variables.h"
 #include "setuid_sandbox_client.h"
@@ -150,6 +151,11 @@ bool SetuidSandboxClient::ChrootMe() {
   return true;
 }
 
+bool SetuidSandboxClient::CreateInitProcessReaper(
+    base::Closure* post_fork_parent_callback) {
+  return sandbox::CreateInitProcessReaper(post_fork_parent_callback);
+}
+
 bool SetuidSandboxClient::IsSuidSandboxUpToDate() const {
   return GetHelperApi(env_) == kSUIDSandboxApiNumber;
 }