Chrome Version       : 52.0.2739.0

What steps will reproduce the problem?
1. Install the password alert extension
2. After awhile try inspecting each of your tabs and look for one where devtools DOESN'T list a context for the content script for the top frame.
3. Set a keypress event breakpoint, click on the main frame (to give it focus) and hit a key

What is the expected result?
Since the password alert content script is apparently not running in the main frame, expect it not to break (or if it does break - show me what code is running and what context it's in).

What happens instead of that?
Debugger breaks but can't generate a stacktrace!  See attached screenshot.  Recording a timeline shows that the content script is infact getting invoked.

It looks like you can also reproduce this by opening a simple page (without any iframes) and immediately inspecting it.  Context list shows only "top" but if you break on keypress you get the same experience of stopping _somewhere_ but without any stack.