Linux: initialize the sandbox in the Plugin process.

content/common/sandbox_seccomp_bpf_linux.cc

Index: content/common/sandbox_seccomp_bpf_linux.cc
diff --git a/content/common/sandbox_seccomp_bpf_linux.cc b/content/common/sandbox_seccomp_bpf_linux.cc
index 446f314f0cf9fd0998fee50de12a064e9f0633ab..83c5d5110b4ba667b25e102c7cbd1f27aad988e0 100644
--- a/content/common/sandbox_seccomp_bpf_linux.cc
+++ b/content/common/sandbox_seccomp_bpf_linux.cc
@@ -1369,6 +1369,10 @@ Sandbox::EvaluateSyscall GetProcessSyscallPolicy(
     return BlacklistDebugAndNumaPolicy;
   }
 
+  if (process_type == switches::kPluginProcess) {
+    return AllowAllPolicy;
+  }
+
   NOTREACHED();
   // This will be our default if we need one.
   return AllowAllPolicy;