The upgrade failed.
But I had backed up all the main folders I might need in case of such a folder.
For reference, these are:
I had to burn the machine and install Yosemite from scratch.
Now one of the things I wanted to recover was the current tabs I had open in Chrome.
The reason being was that some of them were very, very interesting and I had not bookmarked them.
I did a little bit of research, but not much turned up.
So I figured it out myself.
Let's say you have a folder ~/OldMachineBackup and it has the folders mentioned above in it.
So to find out what tabs you had open:
cd ~/OldMachineBackup strings Application\ Support/Google/Chrome/Default/Current\ Tabs | egrep '^http' | sort | uniq
And there you have them. A list of http addresses.