This repros at least as far back as Version 50.0.2628.0, so it's not a recent regression.

This is pretty funny.

 // Works.
 var a= window.open("about:blank");
 // Fails.
 var a= window.open("");

This fails inside browser_commands.cc's ShowPageInfo function:

bool ShowPageInfo(Browser* browser, content::WebContents* web_contents) {
  content::NavigationEntry* entry =
      web_contents->GetController().GetVisibleEntry();
  if (!entry) {
    return false;
  }

That, in turn, fails because GetVisibleEntry() returns null because GetLastCommittedEntry() returns null in the case where the window.open went to an empty string rather than about:blank.

Interesting.  It's probably worth updating ShowPageInfo to handle this case, but I'll also mention that I have some long term plans to make sure there's a NavigationEntry for the initial empty page in issue 524208.  (I tried a while ago, and I ran into too many odd tests and dependencies at the time.  I'll probably give it a try again in the future.)

I'll mark this as low-priority for now.

Happy to reprioritize if there are security inplications.

This is  issue 547982 .

Re #5: It's certainly related, in that it's another example of a downstream consequence of Issue 524208. To me, the surprising part of this is that window.open("") and window.open("about:blank") aren't being handled in exactly the same way.