Scott: you broke it, you bought it. :-)  I have reason to believe that r362258 is responsible. I think that crashpad's use of logging::SetLogMessageHandler (to capture FATAL messages?) kicks out the one here

  https://cs.chromium.org/chromium/src/base/logging_win.cc?dr=C&q=SetLogMessageHandler+file:logging_win%5C.cc&sq=package:chromium&l=105

that is registered during setup.exe startup here

  https://cs.chromium.org/chromium/src/chrome/installer/util/logging_installer.cc?dr=CSs&q=InitInstallerLogging+file:logging_installer%5C.cc&sq=package:chromium&l=74

I'm guessing that crashpad's handler is getting overridden by Chrome's in the browser process

  https://cs.chromium.org/chromium/src/chrome/common/logging_chrome.cc?dr=C&q=LogEventProvider::Initialize+file:logging_chrome%5C.cc&sq=package:chromium&l=361

wychen (CCd) was working on something in https://codereview.chromium.org/2034393004/ that would resolve this. wychen: what's the status of that CL?

I guess we have a couple attempts at fixing related things

https://codereview.chromium.org/2377963002/
https://codereview.chromium.org/2034393004/

Hopefully one can land soonish.

(It's possible it's a chrome_elf vs chrome thing too, rather than an override? I'm not sure, I haven't dug into it yet.)