Fix some extern usage in .cc files.

chrome/browser/extensions/api/cookies/cookies_api_constants.cc

 // 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.
 
 #include "chrome/browser/extensions/api/cookies/cookies_api_constants.h"
 
 namespace extensions {
 namespace cookies_api_constants {
 
 // Keys
 const char kCauseKey[] = "cause";
 const char kCookieKey[] = "cookie";
 const char kDomainKey[] = "domain";
 const char kIdKey[] = "id";
 const char kRemovedKey[] = "removed";
 const char kTabIdsKey[] = "tabIds";
 
 // Cause Constants
-extern const char kEvictedChangeCause[] = "evicted";
-extern const char kExpiredChangeCause[] = "expired";
-extern const char kExpiredOverwriteChangeCause[] = "expired_overwrite";
-extern const char kExplicitChangeCause[] = "explicit";
-extern const char kOverwriteChangeCause[] = "overwrite";
+const char kEvictedChangeCause[] = "evicted";
+const char kExpiredChangeCause[] = "expired";
+const char kExpiredOverwriteChangeCause[] = "expired_overwrite";
+const char kExplicitChangeCause[] = "explicit";
+const char kOverwriteChangeCause[] = "overwrite";
 
 // Errors
 const char kCookieSetFailedError[] =
     "Failed to parse or set cookie named \"*\".";
 const char kInvalidStoreIdError[] = "Invalid cookie store id: \"*\".";
 const char kInvalidUrlError[] = "Invalid url: \"*\".";
 const char kNoCookieStoreFoundError[] =
     "No accessible cookie store found for the current execution context.";
 const char kNoHostPermissionsError[] =
     "No host permissions for cookies at url: \"*\".";
 
 }  // namespace cookies_api_constants
 }  // namespace extensions