Move ".crx"/".pem" constants and extension_filenames constants into extensions/common/constants.cc.

chrome/common/extensions/extension_l10n_util_unittest.cc

Index: chrome/common/extensions/extension_l10n_util_unittest.cc
diff --git a/chrome/common/extensions/extension_l10n_util_unittest.cc b/chrome/common/extensions/extension_l10n_util_unittest.cc
index e5194ffac7c58e990c2d605e8b83077216076aa7..f7a40738f2304f8471db758f865789577b67f091 100644
--- a/chrome/common/extensions/extension_l10n_util_unittest.cc
+++ b/chrome/common/extensions/extension_l10n_util_unittest.cc
@@ -17,8 +17,8 @@
 #include "testing/gtest/include/gtest/gtest.h"
 #include "ui/base/l10n/l10n_util.h"
 
-using extensions::kLocaleFolder;
-using extensions::kMessagesFilename;
+using extensions::filenames::kLocaleFolder;
+using extensions::filenames::kMessagesFilename;
 using extensions::MessageBundle;
 
 namespace errors = extension_manifest_errors;