Introduce sky_packager

sky/tools/packager/logging.h

 // Copyright 2015 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.
 
-#ifndef SKY_ENGINE_TONIC_DART_ERROR_H_
-#define SKY_ENGINE_TONIC_DART_ERROR_H_
+#ifndef SKY_TOOLS_PACKAGER_LOGGING_H_
+#define SKY_TOOLS_PACKAGER_LOGGING_H_
+
+#include <string>
 
 #include "dart/runtime/include/dart_api.h"
 
-namespace blink {
+bool LogIfError(Dart_Handle handle);
+std::string StringFromDart(Dart_Handle string);
+Dart_Handle StringToDart(const std::string& string);
 
-namespace DartError {
-extern const char kInvalidArgument[];
-}  // namespace DartError
-
-bool LogIfError(Dart_Handle handle);
-
-}  // namespace blink
-
-#endif  // SKY_ENGINE_TONIC_DART_ERROR_H_
-
+#endif  // SKY_TOOLS_PACKAGER_LOGGING_H_