From Chrome Web Store users can download extensions, apps and themes for Google Chrome browser and since these extensions are approved by Google they are safe to download and install on your browser, Google now saying they’re seeing increase in downloads from Chrome Web Store because of inline installation feature launched few months ago.
What is inline Installation of Chrome apps and extensions?
Since it is tough to find extensions from Chrome web store, developer can add a link to his extension hosted in Chrome Web Store and initiate apps and extensions installations “ inline” from his site so that user without navigating away from developer’s site can install extension on his browser, where extension will be installed from Chrome web store.
Evernote for and Rovio for their extensions ( Evernote clearly, Evernote Web Clipper and Angry Birds Chrome) implemented inline installation from their sites and saw increase in installations. So Google now asking developers to implement inline installations to increase their extensions/apps downloads and installations from Chrome Web Store.
Source : Chromium blog