Stop using chrome-sandbox to determine real pids

components/nacl/loader/nacl_helper_linux.cc

Index: components/nacl/loader/nacl_helper_linux.cc
diff --git a/components/nacl/loader/nacl_helper_linux.cc b/components/nacl/loader/nacl_helper_linux.cc
index 15f58eb3a5fba07e50a7b578f240a261be23384e..91dd855081d562de716a880580a1d1f21f1afa3b 100644
--- a/components/nacl/loader/nacl_helper_linux.cc
+++ b/components/nacl/loader/nacl_helper_linux.cc
@@ -34,6 +34,7 @@
 #include "components/nacl/loader/nacl_listener.h"
 #include "components/nacl/loader/nacl_sandbox_linux.h"
 #include "components/nacl/loader/nonsfi/nonsfi_sandbox.h"
+#include "content/public/common/child_process_sandbox_support_linux.h"
 #include "content/public/common/zygote_fork_delegate_linux.h"
 #include "crypto/nss_util.h"
 #include "ipc/ipc_descriptors.h"
@@ -143,40 +144,11 @@ void ChildNaClLoaderInit(const std::vector<int>& child_fds,
                          bool uses_nonsfi_mode,
                          const std::string& channel_id) {
   const int parent_fd = child_fds[content::ZygoteForkDelegate::kParentFDIndex];
-  const int dummy_fd = child_fds[content::ZygoteForkDelegate::kDummyFDIndex];
-
-  bool validack = false;
-  base::ProcessId real_pid;
-  // Wait until the parent process has discovered our PID.  We
-  // should not fork any child processes (which the seccomp
-  // sandbox does) until then, because that can interfere with the
-  // parent's discovery of our PID.
-  const ssize_t nread =
-      HANDLE_EINTR(read(parent_fd, &real_pid, sizeof(real_pid)));
-  if (static_cast<size_t>(nread) == sizeof(real_pid)) {
-    // Make sure the parent didn't accidentally send us our real PID.
-    // We don't want it to be discoverable anywhere in our address space
-    // when we start running untrusted code.
-    CHECK(real_pid == 0);
-
-    CommandLine::ForCurrentProcess()->AppendSwitchASCII(
-        switches::kProcessChannelID, channel_id);
-    validack = true;
-  } else {
-    if (nread < 0)
-      perror("read");
-    LOG(ERROR) << "read returned " << nread;
-  }
-
-  if (IGNORE_EINTR(close(dummy_fd)) != 0)
-    LOG(ERROR) << "close(dummy_fd) failed";
+  if (!content::SendRealPidToZygote(parent_fd, NULL))
+    LOG(FATAL) << "Failed to synchronize with zygote";
   if (IGNORE_EINTR(close(parent_fd)) != 0)
-    LOG(ERROR) << "close(parent_fd) failed";
-  if (validack) {
-    BecomeNaClLoader(child_fds, system_info, uses_nonsfi_mode);
-  } else {
-    LOG(ERROR) << "Failed to synch with zygote";
-  }
+    LOG(FATAL) << "close(parent_fd) failed";
+  BecomeNaClLoader(child_fds, system_info, uses_nonsfi_mode);
   _exit(1);
 }