Service Worker: Add metrics and timeout for starting a Service Worker.

content/common/service_worker/service_worker_status_code.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_COMMON_SERVICE_WORKER_SERVICE_WORKER_STATUS_CODE_H_
 #define CONTENT_COMMON_SERVICE_WORKER_SERVICE_WORKER_STATUS_CODE_H_
 
 #include "content/common/content_export.h"
 
 namespace content {
 
 // Generic service worker operation statuses.
+// This enum is used in UMA histograms, so don't change the order or remove
+// entries.
 enum ServiceWorkerStatusCode {
   // Operation succeeded.
   SERVICE_WORKER_OK,
 
   // Generic operation error (more specific error code should be used in
   // general).
   SERVICE_WORKER_ERROR_FAILED,
 
   // Operation was aborted (e.g. due to context or child process shutdown).
   SERVICE_WORKER_ERROR_ABORT,
@@ skipping 24 matching lines @@
   SERVICE_WORKER_ERROR_NETWORK,
 
   // Operation is failed by security issue.
   SERVICE_WORKER_ERROR_SECURITY,
 
   // Event handling failed (event.waitUntil Promise rejected).
   SERVICE_WORKER_ERROR_EVENT_WAITUNTIL_REJECTED,
 
   // An error triggered by invalid worker state.
   SERVICE_WORKER_ERROR_STATE,
+
+  // The Service Worker took too long to finish a task.
+  SERVICE_WORKER_ERROR_TIMEOUT,
+
+  SERVICE_WORKER_ERROR_MAX_VALUE
 };
 
 CONTENT_EXPORT const char* ServiceWorkerStatusToString(
     ServiceWorkerStatusCode code);
 
 }  // namespace content
 
 #endif  // CONTENT_COMMON_SERVICE_WORKER_SERVICE_WORKER_STATUS_CODE_H_