How to change ctrl-shift-j shortcut on Google Chrome?

If you are on the Mac, you can always use the keyboard prefpane to change an hotkey. Just open Keyboard and go to hotkeys. There you can redefine any hotkey in any program you want.

There's an extension for remapping shortcuts that might be useful: https://chrome.google.com/extensions/detail/mgjjeipcdnnjhgodgjpfkffcejoljijf. Haven't tried it yet though.

This question is no longer relevant since Chrome added the F12 shortcut.