David, Adam: Are there any plans for this on the BoringSSL side?

I'm marking this as all platforms, but here's the status:
- For macOS, either macOS would need to add support, or we transition off using macOS crypto APIs. So ExternalDependency on macOS, or on moving off macOS Security.frameowrk.
- For Linux/ChromeOS users, either NSS would need to add support, or we transition off using NSS crypto APIs for certificate validation. So ExternalDependency on NSS or on moving off NSS
- For Android, either Android would need to add support (via Conscrypt), or we transition off using Android crypto APIs. So ExternalDepedency on Android platform or moving off Android security APIs. For Android security APIs to add it, we generally need BoringSSL to support it and the Java JCE provider APIs to expose it.
- For Windows, either Microsoft would need to add support (to CNG), we'd need to develop our own CNG provider and inject that, or we transition off Microsoft's CNG/CryptoAPI framework for certificate validation.

So marking it P-3/Feature/ExternalDependency. I don't believe we'd want to partially transition Chrome on its supported platforms due to ecosystem risk.

I'm ignoring iOS in the room, but iOS fully uses iOS Security.framework APIs due to WKWebView and there are no plans to change that. So iOS is fully with Apple.