I'd like for my chrome extension to reload every time I save a file in the extension folder, without having to explicitly click "reload" in chrome://extensions/. Is this possible?
Edit: I'm aware I can update the interval at which Chrome reloads extensions, which is a half-way solution, but I'd rather either making my editor (emacs or textmate) trigger on-save a reload or asking Chrome to monitor the directory for changes.
It can't be done directly. Sorry.
If you would like to see it as a feature you can request it at http://crbug.com/new
Chrome Extensions have a permission system that it wouldn't allow it (some people in SO had the same problem as you), so requesting them to "add this feature" is not going to work IMO. There's a mail from Chromium Extensions Google Groups with a proposed solution (theory) using chrome.extension.getViews(), but is not guaranteed to work either.
If it was possible to add to the manifest.json some Chrome internal pages like chrome://extensions/, it would be possible to create a plugin that would interact to the Reload anchor, and, using an external program like XRefresh (a Firefox Plugin - there's a Chrome version using Ruby and WebSocket), you would achieve just what you need:
XRefresh is a browser plugin which will refresh current web page due to file change in selected folders. This makes it possible to do live page editing with your favorite HTML/CSS editor.
It's not possible to do it, but I think you can use this same concept in a different way.
You could try to find third-party solutions instead that, after seeing modifications in a file (I don't know emacs neither Textmate, but in Emacs it would be possible to bind an app call within a "save file" action), just clicks in an specific coordinate of an specific application: in this case it's the Reload anchor from your extension in development (you leave a Chrome windows opened just for this reload).
(Crazy as hell but it may work)
Your content files such has html and manifest files are not changeable without installation of the extension, but I do believe that the JavaScript files are dynamically loaded until the extension has been packed.
I know this because of a current project im working on via the Chrome Extensions API, and seems to load every-time i refresh a page.