AU: Bzip2 utility functions that mirror Gzip utility functions.

Also, Convert the gzip_unittest into a typed test and use the same
test cases for bzip2.

Review URL: http://codereview.chromium.org/855002
diff --git a/bzip.h b/bzip.h
new file mode 100644
index 0000000..ca6e881
--- /dev/null
+++ b/bzip.h
@@ -0,0 +1,16 @@
+// 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 <string>
+#include <vector>
+
+namespace chromeos_update_engine {
+
+// Bzip2 compresses or decompresses str/in to out.
+bool BzipDecompress(const std::vector<char>& in, std::vector<char>* out);
+bool BzipCompress(const std::vector<char>& in, std::vector<char>* out);
+bool BzipCompressString(const std::string& str, std::vector<char>* out);
+bool BzipDecompressString(const std::string& str, std::vector<char>* out);
+
+}  // namespace chromeos_update_engine