ServiceWorker: Add UMA for ServiceWorkerDatabase

content/browser/service_worker/service_worker_database.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_DATABASE_H_
 #define CONTENT_BROWSER_SERVICE_WORKER_SERVICE_WORKER_DATABASE_H_
 
 #include <map>
 #include <set>
 #include <vector>
@@ skipping 21 matching lines @@
 // Should NOT be used on the IO thread since this does blocking
 // file io. The ServiceWorkerStorage class owns this class and
 // is responsible for only calling it serially on background
 // non-IO threads (ala SequencedWorkerPool).
 class CONTENT_EXPORT ServiceWorkerDatabase {
  public:
   // We do leveldb stuff in |path| or in memory if |path| is empty.
   explicit ServiceWorkerDatabase(const base::FilePath& path);
   ~ServiceWorkerDatabase();
 
   enum Status {

[michaeln, 2014/05/29 23:46:28]

please comment about these being used in uma so future changes should  append
only

[nhiroki, 2014/06/02 04:54:47]

Done.

     STATUS_OK,
     STATUS_ERROR_NOT_FOUND,
+    STATUS_ERROR_IO_ERROR,
     STATUS_ERROR_CORRUPTED,
     STATUS_ERROR_FAILED,
+    STATUS_ERROR_MAX,
   };
 
   struct CONTENT_EXPORT RegistrationData {
     // These values are immutable for the life of a registration.
     int64 registration_id;
     GURL scope;
     GURL script;
 
     // Versions are first stored once they successfully install and become
     // the waiting version. Then transition to the active version. The stored
@@ skipping 241 matching lines @@
   FRIEND_TEST_ALL_PREFIXES(ServiceWorkerDatabaseTest, OpenDatabase_InMemory);
   FRIEND_TEST_ALL_PREFIXES(ServiceWorkerDatabaseTest, DatabaseVersion);
   FRIEND_TEST_ALL_PREFIXES(ServiceWorkerDatabaseTest, GetNextAvailableIds);
 
   DISALLOW_COPY_AND_ASSIGN(ServiceWorkerDatabase);
 };
 
 }  // namespace content
 
 #endif  // CONTENT_BROWSER_SERVICE_WORKER_SERVICE_WORKER_DATABASE_H_