OS: Chrome

We should add the ability to adjust the volume of ChromeVox speech separate from the system audio volume. We could begin by adding this functionality through a keyboard command like Search + Volume Up and Search + Volume Down to adjust the ChromeVox volume. Eventually, it would also be great to determine a touch gesture to map to this functionality, particularly for using CFM touch machines. 

The volume should never be able to go below 25% though, as to not create confusion for users who turned down the volume of ChromeVox all the way and can't figure out why it's not speaking. We should also consider that every time you turn ChromeVox off then on again, that we should reset the ChromeVox volume to default, again to avoid any user confusion.