Using webkit or blink (chrome) directly, instead of via a browser, will not help you much. Same deps, almost the same RAM usage, etc etc. The difference is you don't have menus, bookmarks, and other browser things outside the page.
You can probably build a native app instead of a web page, but it all depends on what you're doing. You've only mentioned you want to show webcam video. A native program is hugely more efficient than a web page in a browser (/engine), no matter what tech you use.