原因
Ubuntu14.04下，除了Chromium未能支持Flash播放器的安装外，其余像Firefox, Chrome浏览器都支持Flash播放器的安装。
从14.04起，Chromium 不再使用 Netscape插件API ,导致原本的 Flash Player 将无法在 Chromium 运行.
要解决这个问题，就需要用Pepper Flash Player。它是一个来自于Google的安全稳定的版本。它已经包含在了Ubuntu 软件仓库中。安装它需要下载Chrome，并从中解压出它。
主要步骤：
sudo apt-get install pepperflashplugin-nonfree
sudo update-pepperflashplugin-nonfree --install 安装
sudo update-pepperflashplugin-nonfree --uninstall 卸载
问题
sudo apt-get install pepperflashplugin-nonfree
出现以下问题：
ERROR: failed to retrieve status information from google : W: There is no public key available for the following key IDs:
1397BC53640DB551
More information might be available at:
http://wiki.debian.org/PepperFlashPlayer
解决方法：
http://unix.stackexchange.com/questions/279825/pepperflashplugin-nonfree-error-failed-to-retrieve-status-information-from-go
pepperflashplugin-nonfree has its own key stash in /usr/lib/pepperflashplugin-nonfree/pubkey-google.txt. Until the package is updated with the new key, you can add the key locally by executing
gpg --keyserver pgp.mit.edu --recv-keys 1397BC53640DB551
gpg --export --armor 1397BC53640DB551 | sudo sh -c 'cat >> /usr/lib/pepperflashplugin-nonfree/pubkey-google.txt'
sudo update-pepperflashplugin-nonfree --install
It is important that the new key is appended to the file (“>>”), the old key is still needed.
After this you can install the pepperflashplugin with
sudo update-pepperflashplugin-nonfree –install
The file will be overwritten when the package is updated, so you might have to do this again after an update if the maintainer hasn’t added the new key (in this case you will get the same error message again when the new version is being installed).
如果/usr/lib/pepperflashplugin-nofree不存在，则：
sudo apt-get update
sudo apt-get install chromium-browser
gpg --keyserver pgp.mit.edu --recv-keys 1397BC53640DB551
gpg --export --armor 1397BC53640DB551 | sudo sh -c 'cat >> /usr/lib/pepperflashplugin-nonfree/pubkey-google.txt'
sudo update-pepperflashplugin-nonfree --install
结果
chrome中输入：chrome://plugins
