Linux Sandbox: add test for one argument system calls.

sandbox/linux/seccomp-bpf/syscall_unittest.cc

Index: sandbox/linux/seccomp-bpf/syscall_unittest.cc
diff --git a/sandbox/linux/seccomp-bpf/syscall_unittest.cc b/sandbox/linux/seccomp-bpf/syscall_unittest.cc
index 374a0fbddd53371a17abdff02a3add9a43eec35f..b00177d2ad5a3801298f33e4883ccffbb79473a3 100644
--- a/sandbox/linux/seccomp-bpf/syscall_unittest.cc
+++ b/sandbox/linux/seccomp-bpf/syscall_unittest.cc
@@ -54,6 +54,14 @@ TEST(Syscall, TrivialSyscallNoArgs) {
   EXPECT_EQ(SandboxSyscall(__NR_getpid), syscall(__NR_getpid));
 }
 
+TEST(Syscall, TrivialSyscallOneArg) {
+  int new_fd;
+  // Duplicate standard error and close it.
+  ASSERT_GE(new_fd = SandboxSyscall(__NR_dup, 2), 0);
+  int close_return_value = HANDLE_EINTR(SandboxSyscall(__NR_close, new_fd));
+  ASSERT_EQ(close_return_value, 0);
+}
+
 TEST(Syscall, ComplexSyscallSixArgs) {
   int fd;
   ASSERT_LE(0, fd = SandboxSyscall(__NR_open, "/dev/null", O_RDWR, 0L));