Fedora22 系统更新软件包，出现：
warning: /var/cache/dnf/google-chrome-eb0d6f10ccbdafba/packages/google-chrome-stable-44.0.2403.157-1.x86_64.rpm: Header V4 DSA/SHA1 Signature, key ID 7fac5991: NOKEY
The downloaded packages were saved in cache till the next successful transaction.
You can remove cached packages by executing 'dnf clean packages'
错误：google-chrome-stable-44.0.2403.157-1.x86_64.rpm 的公钥没有安装
主要原因是安装的google-chrome包的公钥没有安装。
解决方法：
dnf update -y --nogpgcheck
我们用选项 --nogpgcheck暂时跳过包签名验证。
参考：https://ask.fedoraproject.org/en/question/31116/how-do-i-install-unsigned-packages-using-yum/
http://unix.stackexchange.com/questions/102814/verify-a-package-installed-with-yum-nogpgcheck-having-gpg-key
Fedora22（Gnome桌面）安装Chrome：http://www.linuxdiyf.com/linux/13134.html
Fedora:快速便捷地安装Chrome：http://www.linuxdiyf.com/linux/11833.html
Linux下正确安装Google Chrome浏览器：http://www.linuxdiyf.com/linux/7220.html