Location of Chrome cache on Mac OS X
The primary cache is nominally
However the bulk of cached data appears in
~/Library/Application Support/Google/Chrome/Default/Application Cache.
If you are a Time Machine user, consider excluding the Application Support directories, as they bloat your backup set. Take care to preserve the bookmarks file if that's important to you, as it's mixed into the same directory.
And if you're using RockMelt build -