Remove stray externs in .cc code

chrome/common/extensions/extension_constants.cc

 // Copyright (c) 2010 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/common/extensions/extension_constants.h"
 
 namespace extension_manifest_keys {
 
 const char* kAllFrames = "all_frames";
 const char* kApp = "app";
@@ skipping 211 matching lines @@
 const char* kInvalidPermissionScheme =
     "Invalid scheme for 'permissions[*]'.";
 const char* kInvalidPlugins =
     "Invalid value for 'plugins'.";
 const char* kInvalidPluginsPath =
     "Invalid value for 'plugins[*].path'.";
 const char* kInvalidPluginsPublic =
     "Invalid value for 'plugins[*].public'.";
 const char* kInvalidRunAt =
     "Invalid value for 'content_scripts[*].run_at'.";
-extern const char* kInvalidSidebar =
+const char* kInvalidSidebar =
     "Invalid value for 'sidebar'.";
-extern const char* kInvalidSidebarDefaultIconPath =
+const char* kInvalidSidebarDefaultIconPath =
     "Invalid value for 'sidebar.default_icon'.";
-extern const char* kInvalidSidebarDefaultTitle =
+const char* kInvalidSidebarDefaultTitle =
     "Invalid value for 'sidebar.default_title'.";
-extern const char* kInvalidSidebarDefaultUrl =
+const char* kInvalidSidebarDefaultUrl =
     "Invalid value for 'sidebar.default_url'.";
 const char* kInvalidSignature =
     "Value 'signature' is missing or invalid.";
 const char* kInvalidTheme =
     "Invalid value for 'theme'.";
 const char* kInvalidThemeColors =
     "Invalid value for theme colors - colors must be integers";
 const char* kInvalidThemeImages =
     "Invalid value for theme images - images must be strings.";
 const char* kInvalidThemeImagesMissing =
@@ skipping 77 matching lines @@
 // The file to write our decoded message catalogs to, relative to the
 // extension_path.
 const char* kDecodedMessageCatalogsFilename = "DECODED_MESSAGE_CATALOGS";
 }
 
 namespace extension_misc {
 const char* kBookmarkManagerId = "eemcgdkfndhakfknompkggombfjjjeno";
 const char* kWebStoreAppId = "ahfgeienlihckogmohjhadlkjgocpleb";
 const char* kAppsPromoHistogram = "Extensions.AppsPromo";
 }