Use tri-state enum for the existence of Fetch Handler in ServiceWorkerVersion.

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 116 matching lines @@
 
   int64_t version_id() const { return version_id_; }
   int64_t registration_id() const { return registration_id_; }
   const GURL& script_url() const { return script_url_; }
   const GURL& scope() const { return scope_; }
   EmbeddedWorkerStatus running_status() const {
     return embedded_worker_->status();
   }
   ServiceWorkerVersionInfo GetInfo();
   Status status() const { return status_; }
-  bool has_fetch_handler() const { return has_fetch_handler_; }
+
+  // This flag is set when the install event has been executed in a new version
+  // or when an installed version is loaded from the storage. When a new version
+  // is not installed yet, returns base::nullopt.
+  base::Optional<bool> has_fetch_handler() const { return has_fetch_handler_; }
   void set_has_fetch_handler(bool has_fetch_handler) {
+    DCHECK(!has_fetch_handler_);
     has_fetch_handler_ = has_fetch_handler;
   }
 
   const std::vector<GURL>& foreign_fetch_scopes() const {
     return foreign_fetch_scopes_;
   }
   void set_foreign_fetch_scopes(const std::vector<GURL>& scopes) {
     foreign_fetch_scopes_ = scopes;
   }
 
@@ skipping 507 matching lines @@
   // Resets |start_worker_first_purpose_| and fires and clears all start
   // callbacks.
   void FinishStartWorker(ServiceWorkerStatusCode status);
 
   const int64_t version_id_;
   const int64_t registration_id_;
   const GURL script_url_;
   const GURL scope_;
   std::vector<GURL> foreign_fetch_scopes_;
   std::vector<url::Origin> foreign_fetch_origins_;
-  bool has_fetch_handler_ = true;
+  base::Optional<bool> has_fetch_handler_;
 
   Status status_ = NEW;
   std::unique_ptr<EmbeddedWorkerInstance> embedded_worker_;
   std::vector<StatusCallback> start_callbacks_;
   std::vector<StatusCallback> stop_callbacks_;
   std::vector<base::Closure> status_change_callbacks_;
 
   // Holds in-flight requests, including requests due to outstanding push,
   // fetch, sync, etc. events.
   IDMap<PendingRequest, IDMapOwnPointer> pending_requests_;
@@ skipping 136 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_