[campd]

Resource usage of devtools that aren't running is near zero (there's a tiny bit of overhead to manage the menu items to launch it).

Download size is affected, although for larger parts of the developer tools (things like firefox OS simulators and adb) we use addons. We think that tradeoff is worth the benefits - users can look under the hood (even if most of them won't), developers have quick and easy access to tools, and we don't have to worry about things like version mismatch/testing concerns/etc.