[extension SW] Support lazy events from extension service workers.

extensions/browser/service_worker_task_queue.h

+// Copyright 2017 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 EXTENSIONS_BROWSER_SERVICE_WORKER_TASK_QUEUE_H_
+#define EXTENSIONS_BROWSER_SERVICE_WORKER_TASK_QUEUE_H_
+
+#include "components/keyed_service/core/keyed_service.h"
+#include "extensions/browser/lazy_context_task_queue.h"
+#include "extensions/common/extension_id.h"
+#include "url/gurl.h"
+
+namespace content {
+class BrowserContext;
+}
+
+namespace extensions {
+class Extension;
+class LazyContextId;
+
+// TODO(lazyboy): This class doesn't queue up any tasks, implement. See
+// LazyBackgroundTaskQueue.
+// TODO(lazyboy): Clean up queue when extension is unloaded/uninstalled.
+class ServiceWorkerTaskQueue : public KeyedService,
+                               public LazyContextTaskQueue {
+ public:
+  explicit ServiceWorkerTaskQueue(content::BrowserContext* browser_context);
+  ~ServiceWorkerTaskQueue() override;
+
+  // Convenience method to return the ServiceWorkerTaskQueue for a given
+  // |context|.
+  static ServiceWorkerTaskQueue* Get(content::BrowserContext* context);
+
+  bool ShouldEnqueueTask(content::BrowserContext* context,
+                         const Extension* extension) override;
+  void AddPendingTaskToDispatchEvent(
+      LazyContextId* context_id,
+      const LazyContextTaskQueue::PendingTask& task) override;
+
+ private:
+  DISALLOW_COPY_AND_ASSIGN(ServiceWorkerTaskQueue);
+};
+
+}  // namespace extensions
+
+#endif  // EXTENSIONS_BROWSER_SERVICE_WORKER_TASK_QUEUE_H_