public static byte[] decodeWebSafe(byte[] source)
      throws Base64DecoderException {
    return decodeWebSafe(source, 0, source.length);
  }
Decodes web safe Base64 content in byte array format and returns
the decoded data.
Web safe encoding uses '-' instead of '+', '_' instead of '/'

@param source the string to decode (decoded in default encoding)
@return the decoded data
android/android_framework/base/src/main/java/com/google/android/vending/licensing/util/Base64.java