NaCl: Add sanity check for number of open FDs at startup

components/nacl/loader/sandbox_linux/nacl_sandbox_linux.h

Index: components/nacl/loader/sandbox_linux/nacl_sandbox_linux.h
diff --git a/components/nacl/loader/sandbox_linux/nacl_sandbox_linux.h b/components/nacl/loader/sandbox_linux/nacl_sandbox_linux.h
index ab6262563870f67eeddb81bd7892d331876e080c..163360b4d9368de5ffa02309d428e95e5330611f 100644
--- a/components/nacl/loader/sandbox_linux/nacl_sandbox_linux.h
+++ b/components/nacl/loader/sandbox_linux/nacl_sandbox_linux.h
@@ -7,6 +7,11 @@
 
 #include "base/files/scoped_file.h"
 #include "base/macros.h"
+#include "base/memory/scoped_ptr.h"
+
+namespace sandbox {
+class SetuidSandboxClient;
+}
 
 namespace nacl {
 
@@ -68,6 +73,7 @@ class NaClSandbox {
   // |proc_fd_| must be released before the layer-1 sandbox is considered
   // enforcing.
   base::ScopedFD proc_fd_;
+  scoped_ptr<sandbox::SetuidSandboxClient> setuid_sandbox_client_;
   DISALLOW_COPY_AND_ASSIGN(NaClSandbox);
 };