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

chrome/browser/extensions/extension_ui_unittest.cc

Index: chrome/browser/extensions/extension_ui_unittest.cc
diff --git a/chrome/browser/extensions/extension_ui_unittest.cc b/chrome/browser/extensions/extension_ui_unittest.cc
index 0ebcde7fea1458e7dc06254718c0bf5049d66e17..84f76c5fe7f4220ff4533317b306c3bac8a5a877 100644
--- a/chrome/browser/extensions/extension_ui_unittest.cc
+++ b/chrome/browser/extensions/extension_ui_unittest.cc
@@ -73,7 +73,7 @@ class ExtensionUITest : public testing::Test {
     std::string error;
 
     base::FilePath manifest_path = extension_path.Append(
-        extensions::kManifestFilename);
+        extensions::filenames::kManifestFilename);
     scoped_ptr<DictionaryValue> extension_data(DeserializeJSONTestData(
         manifest_path, &error));
     EXPECT_EQ("", error);