Implement a poor man's PostAfterStartupTask() function.

content/browser/service_worker/service_worker_register_job.cc

Index: content/browser/service_worker/service_worker_register_job.cc
diff --git a/content/browser/service_worker/service_worker_register_job.cc b/content/browser/service_worker/service_worker_register_job.cc
index 0a28dc1ccab0af6b23f99e53b9b04f4f851599e6..87005e571233898510c7e5ebce61352ebe8b9926 100644
--- a/content/browser/service_worker/service_worker_register_job.cc
+++ b/content/browser/service_worker/service_worker_register_job.cc
@@ -13,6 +13,7 @@
 #include "content/browser/service_worker/service_worker_storage.h"
 #include "content/browser/service_worker/service_worker_utils.h"
 #include "content/common/service_worker/service_worker_types.h"
+#include "content/public/browser/browser_thread.h"
 #include "net/base/net_errors.h"
 
 namespace content {
@@ -81,6 +82,16 @@ void ServiceWorkerRegisterJob::AddCallback(
 
 void ServiceWorkerRegisterJob::Start() {
   SetPhase(START);
+  BrowserThread::PostAfterStartupTask(
+      FROM_HERE,
+      base::MessageLoop::current()->task_runner(),
+      base::Bind(&ServiceWorkerRegisterJob::StartInternal,
+                  weak_factory_.GetWeakPtr()));
+}
+
+void ServiceWorkerRegisterJob::StartInternal() {
+  if (phase_ != START)
+    return;
   ServiceWorkerStorage::FindRegistrationCallback next_step;
   if (job_type_ == REGISTRATION_JOB) {
     next_step = base::Bind(