buffet: extract useful error code definitionss into a separate file

Moved json parser error information from http_utils into its own
file, error_codes.h/.cc, where all future common error codes would
go.

BUG=None
TEST=USE=buffet P2_TEST_FILTER="buffet::*" FEATURES=test emerge-link platform2

Change-Id: Ie5457cedc248612ab512a7161b1fc2cb75758ac5
Reviewed-on: https://chromium-review.googlesource.com/209248
Tested-by: Alex Vakulenko <avakulenko@chromium.org>
Reviewed-by: Christopher Wiley <wiley@chromium.org>
Commit-Queue: Alex Vakulenko <avakulenko@chromium.org>
diff --git a/buffet/error_codes.cc b/buffet/error_codes.cc
new file mode 100644
index 0000000..bf51efc
--- /dev/null
+++ b/buffet/error_codes.cc
@@ -0,0 +1,22 @@
+// Copyright 2014 The Chromium OS 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 "buffet/error_codes.h"
+
+namespace buffet {
+namespace errors {
+
+namespace json {
+const char kDomain[] = "json_parser";
+const char kParseError[] = "json_parse_error";
+const char kObjectExpected[] = "json_object_expected";
+}  // namespace json
+
+namespace file_system {
+const char kDomain[] = "file_system";
+const char kFileReadError[] = "file_read_error";
+}  // namespace file_system
+
+}  // namespace errors
+}  // namespace buffet