Repro: 
1. turn PG on in PG switcher extension.
2. Visit administration link, such as project angle/angle settings
https://chromium-review.googlesource.com/#/admin/projects/angle/angle
3. Get redirected to https://chromium-review.googlesource.com/admin/projects/angle/angle and stare at a blank content page with a typical PG header and footer (example: https://screenshot.googleplex.com/hXXrhzf5EA6.png)