Add ref count to service workers for extension API.

content/browser/service_worker/service_worker_context_wrapper.h

Index: content/browser/service_worker/service_worker_context_wrapper.h
diff --git a/content/browser/service_worker/service_worker_context_wrapper.h b/content/browser/service_worker/service_worker_context_wrapper.h
index 12c8b7220cd833464c774c76357a7bb6408573c5..d8ac7a22c97746718e7699b9b80f5c5d5fd874b8 100644
--- a/content/browser/service_worker/service_worker_context_wrapper.h
+++ b/content/browser/service_worker/service_worker_context_wrapper.h
@@ -112,6 +112,8 @@ class CONTENT_EXPORT ServiceWorkerContextWrapper
       blink::WebNavigationHintType type,
       int render_process_id,
       const ResultCallback& callback) override;
+  bool IncrementPendingActivity(int64_t service_worker_version_id) override;
+  bool DecrementPendingActivity(int64_t service_worker_version_id) override;
 
   // These methods must only be called from the IO thread.
   ServiceWorkerRegistration* GetLiveRegistration(int64_t registration_id);
@@ -196,6 +198,7 @@ class CONTENT_EXPORT ServiceWorkerContextWrapper
   friend class base::RefCountedThreadSafe<ServiceWorkerContextWrapper>;
   friend class EmbeddedWorkerTestHelper;
   friend class EmbeddedWorkerBrowserTest;
+  friend class ServiceWorkerContext;
   friend class ServiceWorkerDispatcherHost;
   friend class ServiceWorkerInternalsUI;
   friend class ServiceWorkerNavigationHandleCore;
@@ -206,6 +209,9 @@ class CONTENT_EXPORT ServiceWorkerContextWrapper
 
   ~ServiceWorkerContextWrapper() override;
 
+  bool IncrementPendingActivityOnIO(int64_t service_worker_version_id);
+  bool DecrementPendingActivityOnIO(int64_t service_worker_version_id);
+
   void InitInternal(
       const base::FilePath& user_data_directory,
       std::unique_ptr<ServiceWorkerDatabaseTaskManager> database_task_manager,
@@ -279,6 +285,10 @@ class CONTENT_EXPORT ServiceWorkerContextWrapper
   // Must be touched on the UI thread.
   std::map<int, int> navigation_hint_task_count_per_process_;
 
+  // Maps service worker version id -> set of pending request ids.
+  // IO thread.
+  std::map<int64_t, std::set<int>> pending_external_requests_;
+
   DISALLOW_COPY_AND_ASSIGN(ServiceWorkerContextWrapper);
 };