Add ref count to service workers for extension API.

content/public/browser/service_worker_context.h

 // Copyright 2014 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_PUBLIC_BROWSER_SERVICE_WORKER_CONTEXT_H_
 #define CONTENT_PUBLIC_BROWSER_SERVICE_WORKER_CONTEXT_H_
 
 #include <set>
 #include <string>
 
@@ skipping 15 matching lines @@
   typedef GURL Scope;
 
   typedef base::Callback<void(bool success)> ResultCallback;
 
   typedef base::Callback<void(const std::vector<ServiceWorkerUsageInfo>&
                                   usage_info)> GetUsageInfoCallback;
 
   typedef base::Callback<void(bool has_service_worker)>
       CheckHasServiceWorkerCallback;
 
+  typedef base::Callback<void(size_t external_request_count)>
+      GetPendingExternalRequestCountCallback;
+
   // Registers the header name which should not be passed to the ServiceWorker.
   // Must be called from the IO thread.
   CONTENT_EXPORT static void AddExcludedHeadersForFetchEvent(
       const std::set<std::string>& header_names);
 
   // Returns true if the header name should not be passed to the ServiceWorker.
   // Must be called from the IO thread.
   static bool IsExcludedHeaderNameForFetchEvent(const std::string& header_name);
 
   // Equivalent to calling navigator.serviceWorker.register(script_url, {scope:
   // pattern}) from a renderer, except that |pattern| is an absolute URL instead
   // of relative to some current origin.  |callback| is passed true when the JS
   // promise is fulfilled or false when the JS promise is rejected.
   //
   // The registration can fail if:
   //  * |script_url| is on a different origin from |pattern|
   //  * Fetching |script_url| fails.
   //  * |script_url| fails to parse or its top-level execution fails.
   //    TODO: The error message for this needs to be available to developers.
   //  * Something unexpected goes wrong, like a renderer crash or a full disk.
   //
   // This function can be called from any thread, but the callback will always
   // be called on the UI thread.
   virtual void RegisterServiceWorker(const Scope& pattern,
                                      const GURL& script_url,
                                      const ResultCallback& callback) = 0;
 
+  // Ref count mechanism for embedder to increment/decrement activity count of a
+  // service worker.
+  // Must be called from the IO thread. Returns whether or not changing the
+  // activity count succeeded.
+  virtual bool IncrementPendingActivity(int64_t service_worker_version_id,

[Devlin, 2016/10/07 15:13:22]

Drive-by: Since these are all associated with a specific uuid, it seems like
maybe this should be "AddPendingActivitiy" and "RemovePendingActivity" (and
maybe make activity_uuid, or replace activity with request in method names?). 
Increment/Decrement makes it sound like there's a separate counter.

But this is really a content/ OWNERS choice, so I'm happy either way - just my
$0.02.

[lazyboy, 2016/10/07 18:50:10]

OK, will do before sending out to content/public review.

[michaeln, 2016/10/07 20:10:30]

i was thinking a rename would be good too, maybe match the naming in the impl

  StartingExternalRequest()
  FinishedExternalRequest()

and later, when needed

  ExtendingExternalRequest() to keep it alive for longer

[lazyboy, 2016/10/07 21:28:41]

Changed the names to reflect this is request instead of activity.

+                                        const std::string& request_uuid) = 0;
+  virtual bool DecrementPendingActivity(int64_t service_worker_version_id,
+                                        const std::string& request_uuid) = 0;
+
   // Equivalent to calling navigator.serviceWorker.unregister(pattern) from a
   // renderer, except that |pattern| is an absolute URL instead of relative to
   // some current origin.  |callback| is passed true when the JS promise is
   // fulfilled or false when the JS promise is rejected.
   //
   // Unregistration can fail if:
   //  * No Service Worker was registered for |pattern|.
   //  * Something unexpected goes wrong, like a renderer crash.
   //
   // This function can be called from any thread, but the callback will always
@@ skipping 16 matching lines @@
   // this still returns true even if there is a Service Worker registration
   // which has a longer match for |other_url|.
   //
   // This function can be called from any thread, but the callback will always
   // be called on the UI thread.
   virtual void CheckHasServiceWorker(
       const GURL& url,
       const GURL& other_url,
       const CheckHasServiceWorkerCallback& callback) = 0;
 
+  // Returns the pending activity count for the worker with the specified
+  // |origin| via |callback|.
+  virtual void GetPendingExternalRequestCountForTest(

[michaeln, 2016/10/07 20:10:30]

and this could be something like CountExternalRequestsFrTest

[lazyboy, 2016/10/07 21:28:41]

Done.

+      const GURL& origin,
+      const GetPendingExternalRequestCountCallback& callback) = 0;
+
   // Stops all running workers on the given |origin|.
   //
   // This function can be called from any thread.
   virtual void StopAllServiceWorkersForOrigin(const GURL& origin) = 0;
 
   // Stops all running service workers and unregisters all service worker
   // registrations. This method is used in LayoutTests to make sure that the
   // existing service worker will not affect the succeeding tests.
   //
   // This function can be called from any thread, but the callback will always
@@ skipping 13 matching lines @@
       const ResultCallback& callback) = 0;
 
  protected:
   ServiceWorkerContext() {}
   virtual ~ServiceWorkerContext() {}
 };
 
 }  // namespace content
 
 #endif  // CONTENT_PUBLIC_BROWSER_SERVICE_WORKER_CONTEXT_H_