download old stable builds of Chromium

gistfile1.txt

Look up the version number (for example "44.0.2403.157") in the Position Lookup
In this case it returns a base position of "330231". This is the commit of where the 44 release was branched, back in May 2015.
Open the continuous builds archive
Click through on your platform (Linux/Mac/Win)
Paste "330231" into the filter field at the top and wait for all the results to XHR in.
Eventually I get a perfect hit: https://commondatastorage.googleapis.com/chromium-browser-snapshots/index.html?prefix=Mac/330231/
Sometimes you may have to decrement the commit number until you find one.

## gitlab-ci.yml:

variables:
    CHROMIUM_URL: https://www.googleapis.com/download/storage/v1/b/chromium-browser-snapshots/o/Linux_x64%2F722276%2Fchrome-linux.zip?alt=media

before_script:
    - apt-get install -y gnupg2
    
     # install Chrome 80.0.3987.106
    - apt-get install zip unzip
    - apt-get install wget
    - apt-get -y install libglib2.0-0
    - apt-get -y install libnss3-dev
    - apt-get -y install libx11-dev
    - wget --output-document chrome-linux64.zip -nv "${CHROMIUM_URL}"
    - unzip -j ./chrome-linux64.zip -d /usr/bin/google-chrome
    - export CHROME_BIN=/usr/bin/google-chrome/chrome