Add ref count to service workers for extension API.

extensions/common/constants.h

 // Copyright (c) 2012 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_COMMON_CONSTANTS_H_
 #define EXTENSIONS_COMMON_CONSTANTS_H_
 
 #include "base/files/file_path.h"
 #include "ui/base/layout.h"
 
@@ skipping 86 matching lines @@
 // rules are stored.
 extern const char kRulesStoreName[];
 
 // The URL query parameter key corresponding to multi-login user index.
 extern const char kAuthUserQueryKey[];
 
 // Mime type strings
 extern const char kMimeTypeJpeg[];
 extern const char kMimeTypePng[];
 
+// TODO(lazyboy): This is a hack and it is copied from service_worker_types.cc,
+// which is not available to extensions/ code. Move the constant to
+// content/public/common.
+extern const int64_t kInvalidServiceWorkerVersionId;
+
 // The extension id of the Web Store component application.
 extern const char kWebStoreAppId[];
 
 // The key used for signing some pieces of data from the webstore.
 extern const uint8_t kWebstoreSignaturesPublicKey[];
 extern const int kWebstoreSignaturesPublicKeySize;
 
 // Enumeration of possible app launch sources.
 // Note the enumeration is used in UMA histogram so entries
 // should not be re-ordered or removed.
@@ skipping 97 matching lines @@
 
 // The extension id for the production version of Hangouts.
 extern const char kProdHangoutsExtensionId[];
 
 // Extension ids used by Hangouts.
 extern const char* const kHangoutsExtensionIds[6];
 
 }  // namespace extension_misc
 
 #endif  // EXTENSIONS_COMMON_CONSTANTS_H_