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

content/browser/service_worker/service_worker_version.h

 // 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.
 
 #ifndef CONTENT_BROWSER_SERVICE_WORKER_SERVICE_WORKER_VERSION_H_
 #define CONTENT_BROWSER_SERVICE_WORKER_SERVICE_WORKER_VERSION_H_
 
 #include <stdint.h>
 
 #include <functional>
@@ skipping 392 matching lines @@
 
   // Returns true if the service worker has work to do: it has pending
   // requests, in-progress streaming URLRequestJobs, or pending start callbacks.
   bool HasWork() const;
 
   // Returns the number of pending external request count of this worker.
   size_t GetExternalRequestCountForTest() const {
     return external_request_uuid_to_request_id_.size();
   }
 
+  // Returns the amount of time left until the request with the latest
+  // expiration time expires.
+  base::TimeDelta remaining_timeout() const {
+    return max_request_expiration_time_ - tick_clock_->NowTicks();
+  }
+
  private:
   friend class base::RefCounted<ServiceWorkerVersion>;
   friend class ServiceWorkerMetrics;
   friend class ServiceWorkerReadFromCacheJobTest;
   friend class ServiceWorkerStallInStoppingTest;
   friend class ServiceWorkerURLRequestJobTest;
   friend class ServiceWorkerVersionBrowserTest;
   friend class ServiceWorkerVersionTestP;
 
   FRIEND_TEST_ALL_PREFIXES(ServiceWorkerControlleeRequestHandlerTestP,
@@ skipping 357 matching lines @@
   base::TimeTicks idle_time_;
   // Holds the time that the outstanding StartWorker() request started.
   base::TimeTicks start_time_;
   // Holds the time the worker entered STOPPING status. This is also used as a
   // trace event id.
   base::TimeTicks stop_time_;
   // Holds the time the worker was detected as stale and needs updating. We try
   // to update once the worker stops, but will also update if it stays alive too
   // long.
   base::TimeTicks stale_time_;
+  // The latest expiration time of all requests that have ever been started. In
+  // particular this is not just the maximum of the expiration times of all
+  // currently existing requests, but also takes into account the former
+  // expiration times of finished requests.

[falken, 2016/12/05 02:31:51]

Thanks for the precise comment.

+  base::TimeTicks max_request_expiration_time_;
 
   // Keeps track of requests for timeout purposes. Requests are sorted by
   // their expiration time (soonest to expire on top of the priority queue). The
   // timeout timer periodically checks |timeout_queue_| for entries that should
   // time out or have already been fulfilled (i.e., removed from
   // |pending_requests_|).
   RequestInfoPriorityQueue timeout_queue_;
 
   bool skip_waiting_ = false;
   bool skip_recording_startup_time_ = false;
@@ skipping 75 matching lines @@
 
   // At this point |this| can have been deleted, so don't do anything other
   // than returning.
 
   return true;
 }
 
 }  // namespace content
 
 #endif  // CONTENT_BROWSER_SERVICE_WORKER_SERVICE_WORKER_VERSION_H_