Convert use_seccomp_bpf to the BUILDFLAG system.

components/nacl/loader/sandbox_linux/nacl_bpf_sandbox_linux.cc

 // Copyright 2013 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "components/nacl/loader/sandbox_linux/nacl_bpf_sandbox_linux.h"
 
 #include <memory>
 #include <utility>
 
 #include "base/macros.h"
 #include "build/build_config.h"
+#include "sandbox/sandbox_features.h"
 
-#if defined(USE_SECCOMP_BPF)
+#if BUILDFLAG(USE_SECCOMP_BPF)
 
 #include <errno.h>
 #include <signal.h>
 #include <sys/ptrace.h>
 #include <sys/types.h>
 #include <unistd.h>
 
 #include "base/callback.h"
 #include "base/command_line.h"
 #include "base/compiler_specific.h"
 #include "base/files/scoped_file.h"
 #include "base/logging.h"
 #include "components/nacl/common/nacl_switches.h"
 #include "content/public/common/sandbox_init.h"
 #include "sandbox/linux/bpf_dsl/bpf_dsl.h"
 #include "sandbox/linux/bpf_dsl/policy.h"
 #include "sandbox/linux/seccomp-bpf-helpers/syscall_parameters_restrictions.h"
 #include "sandbox/linux/system_headers/linux_syscalls.h"
 
-#endif  // defined(USE_SECCOMP_BPF)
+#endif  // BUILDFLAG(USE_SECCOMP_BPF)
 
 namespace nacl {
 
-#if defined(USE_SECCOMP_BPF)
+#if BUILDFLAG(USE_SECCOMP_BPF)
 
 namespace {
 
 using sandbox::bpf_dsl::Allow;
 using sandbox::bpf_dsl::Error;
 using sandbox::bpf_dsl::ResultExpr;
 
 class NaClBPFSandboxPolicy : public sandbox::bpf_dsl::Policy {
  public:
   NaClBPFSandboxPolicy()
@@ skipping 108 matching lines @@
   // Without the sandbox on, this ptrace call would ESRCH instead.
   CHECK_EQ(EPERM, errno);
 }
 
 }  // namespace
 
 #else
 
 #error "Seccomp-bpf disabled on supported architecture!"
 
-#endif  // defined(USE_SECCOMP_BPF)
+#endif  // BUILDFLAG(USE_SECCOMP_BPF)
 
 bool InitializeBPFSandbox(base::ScopedFD proc_fd) {
-#if defined(USE_SECCOMP_BPF)
+#if BUILDFLAG(USE_SECCOMP_BPF)
   bool sandbox_is_initialized = content::InitializeSandbox(
       std::unique_ptr<sandbox::bpf_dsl::Policy>(new NaClBPFSandboxPolicy),
       std::move(proc_fd));
   if (sandbox_is_initialized) {
     RunSandboxSanityChecks();
     return true;
   }
-#endif  // defined(USE_SECCOMP_BPF)
+#endif  // BUILDFLAG(USE_SECCOMP_BPF)
   return false;
 }
 
 }  // namespace nacl