I tried adding [Measure, MeasureAs=CookieStoreAPI] to CookieStore's methods in //third_party/blink/renderer/modules/cookie_store/cookie_store.idl. I was hoping to get 2 counters -- one for the particular method, and one for the whole API.

I looked at the generated code. It uses the [Measure] counter in most branches for each method, except for the "if (true)" branch -- https://cs.chromium.org/chromium/src/out/Debug/gen/third_party/blink/renderer/bindings/modules/v8/v8_cookie_store.cc?l=183

If I'm reading the generated code correctly, it seems like my usage will be split across the 2 counters. Please consider either supporting this use case, or throwing an error when processing an IDL that has both attributes on the same entity.