Add UMA for service worker navigation preload.

content/browser/service_worker/service_worker_url_request_job.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_BROWSER_SERVICE_WORKER_SERVICE_WORKER_URL_REQUEST_JOB_H_
 #define CONTENT_BROWSER_SERVICE_WORKER_SERVICE_WORKER_URL_REQUEST_JOB_H_
 
 #include <stdint.h>
 
 #include <map>
@@ skipping 275 matching lines @@
 
   bool response_is_in_cache_storage_ = false;
   std::string response_cache_storage_cache_name_;
 
   ServiceWorkerHeaderList cors_exposed_header_names_;
 
   std::unique_ptr<FileSizeResolver> file_size_resolver_;
 
   bool worker_already_activated_ = false;
   EmbeddedWorkerStatus initial_worker_status_ = EmbeddedWorkerStatus::STOPPED;
+  bool did_navigation_preload_ = false;
 
   base::WeakPtrFactory<ServiceWorkerURLRequestJob> weak_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(ServiceWorkerURLRequestJob);
 };
 
 }  // namespace content
 
 #endif  // CONTENT_BROWSER_SERVICE_WORKER_SERVICE_WORKER_URL_REQUEST_JOB_H_