Google added option to Allow only Sandboxed plug-ins to run in Google Chrome Canary build under content settings, what this means is as Chrome has native PDF plug-in which runs inside Chrome’s sandbox will only run in Chrome and other plugins will be blocked from loading if this option is selected by the user.

allow only sandboxed plug-ins

With  built-in PDF plug-in running inside Google Chrome’s sandbox PDF-based vulnerabilities will not install malware into user’s Computer.

Click to play aka Flashblock built-in feature

Google Chrome canary build also got built in flash block feature or click to play feature enabled by default which allows to activate plugins on per page basis .

If user chooses to “ Do not allow any site to use plug-ins” from content settings then with click to play feature enabled user can allow the plug-in to run on that page only.