cookiesmacos
Where are Google Chrome cookies located on a mac?
I went
~/Library/Application Support/Google/Chrome/Default/Cookies, but I don't think that this file is the one. I cleared cookies, went to this file, copied content, brows a little, paste the content i copied back into the file and saved. I was still logged in gmail.
The preference goes in the com.google.Chrome.manifest file.
Open the manifest folder with the following Terminal command.
open /Applications/Google\ Chrome.app/Contents/Resources/com.google.Chrome.manifest/Contents/Resources/
This presumes Google Chrome is in /Applications; adjust if necessary. Make sure to copy the entire line.
Open com.google.Chrome.manifest. I will use TextMate.
The AutoSelectCertificateForUrls preference goes on line 174.
Alternatively, use ⌘F to search for AutoSelectCertificateForUrls then select the pfm_targets array.
Replace user-managed with your preference string, per the example in the link you gave.
{\"pattern\":\"https://www.example.com\",\"filter\":{\"ISSUER\":{\"CN\":\"certificate issuer name\"}}}
Alternatively, you can use Workgroup Manager to set the preference.
Download and open Workgroup Manager.
Connect to localhost with an admin account.
Choose the User tab, and enter your username, then select your account.
Select Preferences in the toolbar, and choose the Details tab.
Add Google Chrome or Chromium to the list by clicking the + button and selecting the application bundle.
Double-click the application that you want to add the preference to, or click it and click the pencil 
button.
Click Always, then choose New Key.
Click New Item, and select Automatically select client certificates for these sites.
Click New Key.
Double-click the Value for 0.
Enter your desired preference string into the box and press enter.
Click Apply Now, then Done.
A managed 
icon should appear next to the app that you added the preference to.
Try this to see if you're just looking in the wrong place...
Quit Chrome
Switch to Finder
Open a new Finder window, Cmd ⌘ N
Go To... Cmd ⌘ Shift ⇧ G
Copy/paste this ~/Library/Application Support/Google/Chrome/Default/ (including the tilde ~) into that Go To window
Hit Enter
What do you see?
Bookmarks ought to be in there, along with Bookmarks.bak
Hold Alt ⌥ & drag both to the desktop, for safety.
Delete Bookmarks.
Rename Bookmarks.bak to Bookmarks
Launch Chrome
BTW, ~ (tilde) is Mac shorthand for your home folder, in My hard drive/my user name/ without needing to know what they are called. It always goes to your home folder.
Best Answer
Session cookies are only stored in memory, but the rest are in
~/Library/Application Support/Google/Chrome/Default/Cookies, it's an sqlite3 database.