zygote: stop using suid sandbox for oom adjust on CrOS

The patch to the kernel that required this usage has been dropped,
so we can drop this suid usage on CrOS now.

Bug: 576409, 850457
Change-Id: I8ea9321f4f233618a239db62a1ecf7a132bc54c8
Reviewed-on: https://chromium-review.googlesource.com/1112815Reviewed-by: Jorge Lucangeli Obes <jorgelo@chromium.org>
Reviewed-by: Greg Kerr <kerrnel@chromium.org>
Reviewed-by: Chris Palmer <palmer@chromium.org>
Commit-Queue: Mike Frysinger <vapier@chromium.org>
Cr-Commit-Position: refs/heads/master@{#570843}

services/service_manager/zygote/host/zygote_host_impl_linux.cc

@@ -102,17 +102,6 @@ void ZygoteHostImpl::Init(const base::CommandLine& command_line) {
           service_manager::switches::kDisableNamespaceSandbox) &&
       sandbox::Credentials::CanCreateProcessInNewUserNS()) {
     use_namespace_sandbox_ = true;
-
-#if defined(OS_CHROMEOS)
-    // Chrome OS has a kernel patch that restricts oom_score_adj. See
-    // https://crbug.com/576409 for details.
-    if (!sandbox_binary_.empty()) {
-      use_suid_sandbox_for_adj_oom_score_ = true;
-    } else {
-      LOG(ERROR) << "SUID sandbox binary is missing. Won't be able to adjust "
-                    "OOM scores.";
-    }
-#endif
   } else if (!command_line.HasSwitch(
                  service_manager::switches::kDisableSetuidSandbox) &&
              !sandbox_binary_.empty()) {