There are several “Screen Capture” extensions available in Google Chrome extension’s gallery but most of them lacks even basic features or a Screen Capture tool. “Screen Capture (by Google)” seems be a good one which is easy to use and does what it says. You can capture visible content of a tab, a region of a web page, or the whole page as a PNG image. It also supports horizontal and vertical scroll when capturing whole page, with an all new auto-save capability.
This extension works on Windows, Linux and Mac as well. You can install this extension from below link