I had to dig for this one.  Found a few references on the web, but either the location has moved since they were posted or the Windows version differs from the Mac version.  At any rate, to view the HTTP headers in Chrome on Mac do the following:

  1. Open a new tab in Chrome
  2. Hit Command-Option-i to bring up the Developer Tools (it’s important you do this before loading the page or the headers won’t be captured)
  3. Load the page you want to view headers for
  4. Switch to your Developer Tools and select Network from the row of buttons across the top
  5. Click the page you loaded on the left-hand side
  6. Click Headers in the new row of tabs underneath the top buttons