I think it just indexes the keywords defined on each application launcher.
In your case, the launcher from "Keyboard" is stored in
/usr/share/applications/gnome-keyboard-panel.desktop and has the following content:
Comment=Change keyboard settings
# Translators: those are keywords for the keyboard control-center panel
If you try each one of the keywords defined there, "Keyboard" is shown as an option in the launcher.
So, if you want to make dash to show Chromium when you type "WWW", just add a
Keywords stanza in
Also, please note that this file probably will be overwritten when Chromium is updated, so probably it would be better to copy the edit file to