Make building seccomp-bpf a GYP condition

content/content_common.gypi

Index: content/content_common.gypi
diff --git a/content/content_common.gypi b/content/content_common.gypi
index 621748a331321b28075bcd3e381e06edfc6a3a32..daa644632386bd1c5762162867a5f0b46af4e59c 100644
--- a/content/content_common.gypi
+++ b/content/content_common.gypi
@@ -635,5 +635,21 @@
       },
      ]
     }],
+    ['use_seccomp_bpf==0', {
+      'sources!': [
+        'common/sandbox_linux/bpf_cros_arm_gpu_policy_linux.cc',
+        'common/sandbox_linux/bpf_cros_arm_gpu_policy_linux.h',
+        'common/sandbox_linux/bpf_gpu_policy_linux.cc',
+        'common/sandbox_linux/bpf_gpu_policy_linux.h',
+        'common/sandbox_linux/bpf_ppapi_policy_linux.cc',
+        'common/sandbox_linux/bpf_ppapi_policy_linux.h',
+        'common/sandbox_linux/bpf_renderer_policy_linux.cc',
+        'common/sandbox_linux/bpf_renderer_policy_linux.h',
+        'common/sandbox_linux/sandbox_bpf_base_policy_linux.cc',
+        'common/sandbox_linux/sandbox_bpf_base_policy_linux.h',
+      ],
+    }, {
+      'defines': ['USE_SECCOMP_BPF'],
+    }],
   ],
 }