Resizes the current window to fill the screen without maximizing.
Changes the window size to be a non-maximized ("restored") window that fills the current monitor's available workspace.
I wrote this so I could go from a maximized window to a non-maximized (but still 'full screen'-sized) window state with one click.
My motivation was that the tab-bar in Chrome is at the very top of the window, and I run Winamp in Windowshade mode along the top edge of my desktop which blocked access to the tabs - by entering a non-maximized state the tabs are pushed-down and become accessible again.
A word on permissions: this extension needs to run content-scripts to access the `window.screen` object which is not currently exposed through the Chrome Extension API. Because the `activeTab` permission does not apply to the Chrome Start Page (which is under `google.com`) it needs permission to run content-scripts on google.com.