Use RecvMsgWithPid to find zygote PID instead of chrome-sandbox

content/zygote/zygote_main_linux.cc

Index: content/zygote/zygote_main_linux.cc
diff --git a/content/zygote/zygote_main_linux.cc b/content/zygote/zygote_main_linux.cc
index 0ec9b438366fc69442e5e42bdeead4c70e01ee25..360cc7a46955810d62e754f9958ca1a46a5ea7da 100644
--- a/content/zygote/zygote_main_linux.cc
+++ b/content/zygote/zygote_main_linux.cc
@@ -23,6 +23,7 @@
 #include "base/linux_util.h"
 #include "base/native_library.h"
 #include "base/pickle.h"
+#include "base/posix/eintr_wrapper.h"
 #include "base/posix/unix_domain_socket_linux.h"
 #include "base/rand_util.h"
 #include "base/sys_info.h"
@@ -344,19 +345,10 @@ static void ZygotePreSandboxInit() {
       new FontConfigIPC(GetSandboxFD()))->unref();
 }
 
-static void CloseFdAndHandleEintr(int fd) {
-  close(fd);
-}
-
 static bool CreateInitProcessReaper() {
-  // This "magic" socket must only appear in one process, so make sure
-  // it gets closed in the parent after fork().
-  base::Closure zygoteid_fd_closer =
-      base::Bind(CloseFdAndHandleEintr, kZygoteIdFd);
   // The current process becomes init(1), this function returns from a
   // newly created process.
-  const bool init_created =
-      sandbox::CreateInitProcessReaper(&zygoteid_fd_closer);
+  const bool init_created = sandbox::CreateInitProcessReaper(NULL);
   if (!init_created) {
     LOG(ERROR) << "Error creating an init process to reap zombies";
     return false;
@@ -460,6 +452,10 @@ bool ZygoteMain(const MainFunctionParams& params,
 
   const bool must_enable_setuid_sandbox =
       linux_sandbox->setuid_sandbox_client()->IsSuidSandboxChild();
+  if (must_enable_setuid_sandbox) {
+    // We have no use for the zygote ID descriptor anymore.

[jln (very slow on Chromium), 2014/04/26 00:54:10]

Maybe be more explicit? "kZygoteIdFd has been passed to US because of an ancient
setuid sandbox ABI requirement. It's a useless dummy, close it."

[mdempsky, 2014/04/26 06:05:58]

Done.

+    CHECK_EQ(0, IGNORE_EINTR(close(kZygoteIdFd)));
+  }
 
   if (forkdelegate != NULL) {
     VLOG(1) << "ZygoteMain: initializing fork delegate";