Squashed 'bundle/virtualclass/' changes from 66b1ca9..6d21234

6d21234 updated code
91db120 updated the screen share code and link of firefox add-on

git-subtree-dir: bundle/virtualclass
git-subtree-split: 6d21234ac33a8b5fbe2707bb2ce146103afbf907
Merge commit '59b8432b64ba920dfe7ade1a1dcaccf15a0b9c2e'