Removes Google Analytics/Urchin tracking parameters (utm_source, utm_medium, etc.) from URLs that are displayed in the address bar. Also cleans up YouTube URLs slightly. This is done as a purely aesthetic post-processing step, the site still sees the parameters at initial loading time. The "cleaned up" URL is ready to be pasted into emails, IMs, etc. Permissions that are required: - "Your browsing history": Necessary to observe when tabs are created and navigated to - "Your data on all websites": Necessary to execute the JavaScript to update the URL without reloading the tab