"With the incredible small size (less than 2MB) and amazingly fast speed, Foxit PDF SDK (DLL) 2.0 is your absolute choice to develop your own PDF applications," suggests Foxit.
Google decided to include two of the most popular plugins (Flash and PDF) in Google Chrome to make the browser more secure. The PDF plugin runs inside Chrome's sandbox so that vulnerabilities can no longer install malware on your computer. The Flash plugin is automatically updated by Google and it's likely that it will run inside Chrome's sandbox in the future. Google Chrome 5 already includes the Flash plugin, while the PDF plugin is available in Google Chrome 6 (dev, beta and soon in the stable channel).
{ Thanks, Tulchin. }