There's an option which does not appear in chromium's manual page --- "-disk-cache-dir".
This option specifies where the disk cache should be stored.
Hence, under Linux, we can set the disk-cache-dir to /dev/null. In that way, the cache will be disabled, and all contents will be read from the Internet directly.

Here is what the modified chromium-browser-chromium.desktop looks like:

[Desktop  Entry] 

Name=Chromium Type=Application 

Comment=Open-source version of Google Chrome web  browser 

Exec=chromium-browser %U --disk-cache-dir=/dev/null 2>/dev/null 

TryExec=chromium-browser 

Icon=chromium-browser

Categories=Network;WebBrowser; 

MimeType=text/html;text/xml;application/xhtml+xml;x-scheme-handler/http;x-scheme-handler/https;