How do I see a history of what I've POST-ed in Google Chrome?

Ok for real, I had to deal with this problem myself and I think I found a reliable solution:

• first don't close the tab which you lost your post data.
• then from the tools menu open task manager of chrome and find the pid.
• afterwards use the process hacker to search for a portion of the string you have lost and continue till you find the longest consecutive data.
• then copy and paste it to a text editor.

This way I was able to save my work today.

The answer by @rad works on Windows but doesn't for Linux. It led me to the following solution for Linux:

1. Don't close the tab
2. Go to Chrome Process Explorer with shift + esc
3. Find Process ID (PID) of tab (e.g. 3982), if you don't see a Process ID column then right click a column title and turn on display
4. Run gcore <PID> // creates the file core.3982 (binary)
5. Then strings core.3982 | less // Converts the binary file to strings for searching, opens dump in Less
6. Then search in less with / followed by enter and use n and p for next and previous results.

This was able to get me a POST that went missing in Chrome on Linux.

There is in fact a (somewhat cumbersome?) method of doing this in Chrome (and, in fact, any WebKit browser with WebInspector).

1. On the page with the form, open the development console. This can be done by pressing F12.
2. In the console that opens up, switch to the Network tab.
   • Optionally, ensure Preserve log is ticked and filter by Documents or XHR, as the case may be.
     
3. Submit your form. Click on the newly created entry and go to the Headers tab. You'll see your submission under Form Data.