Linux sandbox: cleanup sandbox-bpf naming.

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 261453bf291f8798e29becba92efa6a036fd1035..60db69bcd6bb5388bb8929740fdef48156cba5ed 100644
--- a/sandbox/linux/seccomp-bpf/syscall_unittest.cc
+++ b/sandbox/linux/seccomp-bpf/syscall_unittest.cc
@@ -18,7 +18,7 @@
 #include "sandbox/linux/tests/unit_tests.h"
 #include "testing/gtest/include/gtest/gtest.h"
 
-using namespace playground2;
+namespace sandbox {
 
 namespace {
 
@@ -78,8 +78,8 @@ intptr_t CopySyscallArgsToAux(const struct arch_seccomp_data& args, void* aux) {
   return -ENOMEM;
 }
 
-ErrorCode CopyAllArgsOnUnamePolicy(Sandbox* sandbox, int sysno, void* aux) {
-  if (!Sandbox::IsValidSyscallNumber(sysno)) {
+ErrorCode CopyAllArgsOnUnamePolicy(SandboxBPF* sandbox, int sysno, void* aux) {
+  if (!SandboxBPF::IsValidSyscallNumber(sysno)) {
     return ErrorCode(ENOSYS);
   }
   if (sysno == __NR_uname) {
@@ -197,3 +197,5 @@ TEST(Syscall, ComplexSyscallSixArgs) {
 }
 
 }  // namespace
+
+}  // namespace sandbox