Linux Sandbox: fix external StartSandbox API

content/common/sandbox_seccomp_bpf_linux.cc

 // Copyright (c) 2012 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 <asm/unistd.h>
 #include <dlfcn.h>
 #include <errno.h>
 #include <fcntl.h>
 #include <linux/audit.h>
 #include <linux/filter.h>
@@ skipping 1930 matching lines @@
     CHECK(started_sandbox);
     return true;
   }
 #endif
   return false;
 }
 
 bool SandboxSeccompBpf::StartSandboxWithExternalPolicy(
     playground2::BpfSandboxPolicy policy) {
 #if defined(SECCOMP_BPF_SANDBOX)
-  if (IsSeccompBpfDesired()) {
+  if (IsSeccompBpfDesired() && SupportsSandbox()) {
     CHECK(policy);
     StartSandboxWithPolicy(policy, NULL);
     return true;
   }
 #endif  // defined(SECCOMP_BPF_SANDBOX)
   return false;
 }
 
 #if defined(SECCOMP_BPF_SANDBOX)
 playground2::BpfSandboxPolicyCallback SandboxSeccompBpf::GetBaselinePolicy() {
   return base::Bind(&BaselinePolicyWithAux);
 }
 #endif  // defined(SECCOMP_BPF_SANDBOX)
 
 }  // namespace content