Don't add NaCl fork delegates to the unsandboxed zygote.

NaCl always starts from the sandboxed zygote, so we don't need
these added. Additionally they trigger a warning message since
the NaCl zygote shouldn't be unsandboxed.

Fixed: 1085552
Change-Id: Ic41e89dda9d06d533cf88d45228a66bd646ed1d1
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2288821
Commit-Queue: Dale Curtis <dalecurtis@chromium.org>
Commit-Queue: Derek Schuff <dschuff@chromium.org>
Reviewed-by: Derek Schuff <dschuff@chromium.org>
Auto-Submit: Dale Curtis <dalecurtis@chromium.org>
Cr-Commit-Position: refs/heads/master@{#786555}

components/nacl/zygote/nacl_fork_delegate_linux.cc

@@ -131,6 +131,13 @@ namespace nacl {
 
 void AddNaClZygoteForkDelegates(
     std::vector<std::unique_ptr<content::ZygoteForkDelegate>>* delegates) {
+  // We don't need the delegates for the unsandboxed zygote since NaCl always
+  // starts from the sandboxed zygote.
+  if (base::CommandLine::ForCurrentProcess()->HasSwitch(
+          sandbox::policy::switches::kNoZygoteSandbox)) {
+    return;
+  }
+
   delegates->push_back(
       std::make_unique<NaClForkDelegate>(false /* nonsfi_mode */));
   delegates->push_back(