Chrome: If you have syncing turned on in Chrome, everything is synced by default: apps, extensions, settings, autofill, Omnibox history, bookmarks, passwords and open tabs. Ever wonder how much data Google has saved or how you can clear it all? Head to the new Chrome Sync page to find out.
Under the Advanced sync settings in Chrome's settings menu, you can select which items you want the browser to sync and set up encryption options (encrypting everything is a good idea). This link will take you directly to the sync settings: chrome://chrome/settings/syncSetup.
Go to the new Chrome Sync page to see how much information is currently stored for syncing. The page doesn't display the actual data, but it tells you if it's stored encrypted by Google, and you can see what data is being stored for each item.
This is also where you should go if you want to clear the synced information. Hitting the "Stop and Clear" button clears all the data -- but be sure you want to do this first, because it's irreversible.