I was just typing a long string of text into an input field in Chrome. I saw my screen flash briefly and the shape of a dialog box appear, but before I could stop typing I had already hit some key that closed the box (I'm guessing space, but possibly a letter or even enter).
How can I find out what the dialog box said and what action I took to close it?
I'm using OS X Yosemite 10.10.5.