Prevent a service worker from keeping itself alive by self postMessage.

content/browser/service_worker/service_worker_version.cc

 // Copyright 2013 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "content/browser/service_worker/service_worker_version.h"
 
 #include <stddef.h>
 
 #include <limits>
 #include <map>
@@ skipping 554 matching lines @@
 
   int request_id = pending_requests_.Add(base::MakeUnique<PendingRequest>(
       error_callback, base::Time::Now(), tick_clock_->NowTicks(), event_type));
   TRACE_EVENT_ASYNC_BEGIN2("ServiceWorker", "ServiceWorkerVersion::Request",
                            pending_requests_.Lookup(request_id), "Request id",
                            request_id, "Event type",
                            ServiceWorkerMetrics::EventTypeToString(event_type));
   base::TimeTicks expiration_time = tick_clock_->NowTicks() + timeout;
   timeout_queue_.push(
       RequestInfo(request_id, event_type, expiration_time, timeout_behavior));
+  if (expiration_time > max_request_expiration_time_)
+    max_request_expiration_time_ = expiration_time;
   return request_id;
 }
 
 bool ServiceWorkerVersion::StartExternalRequest(
     const std::string& request_uuid) {
   // It's possible that the renderer is lying or the version started stopping
   // right around the time of the IPC.
   if (running_status() != EmbeddedWorkerStatus::RUNNING)
     return false;
 
@@ skipping 1292 matching lines @@
 
 void ServiceWorkerVersion::CleanUpExternalRequest(
     const std::string& request_uuid,
     ServiceWorkerStatusCode status) {
   if (status == SERVICE_WORKER_OK)
     return;
   external_request_uuid_to_request_id_.erase(request_uuid);
 }
 
 }  // namespace content