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 42 matching lines @@
   //  * |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;
 
+  virtual bool IncrementPendingActivity(int64_t service_worker_version_id) = 0;
+  virtual bool DecrementPendingActivity(int64_t service_worker_version_id) = 0;

[falken, 2016/09/29 14:52:25]

Could you add brief comments including that these must be called on IO thread?

[lazyboy, 2016/09/29 18:07:20]

Done.

+
   // 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 49 matching lines @@
       const ResultCallback& callback) = 0;
 
  protected:
   ServiceWorkerContext() {}
   virtual ~ServiceWorkerContext() {}
 };
 
 }  // namespace content
 
 #endif  // CONTENT_PUBLIC_BROWSER_SERVICE_WORKER_CONTEXT_H_