There are two copies of sizes.py:
https://cs.chromium.org/chromium/build/scripts/slave/chromium/sizes.py
https://cs.chromium.org/chromium/src/infra/scripts/legacy/scripts/slave/chromium/sizes.py

And resource_sizes.py is here:
https://cs.chromium.org/chromium/src/build/android/resource_sizes.py

sizes.py is used only for desktop (and cronet?), and dumps a few key ELF section sizes, as well as static initializer count.

resource_sizes.py dumps many metrics about the make-up of an APK, and also static initializer count.

size.py static initializers are checked by trybots via checked-in expectations here:
https://cs.chromium.org/chromium/src/tools/perf_expectations/perf_expectations.json

resource_sizes.py static initializers are checked via a build target:
//chrome/android:monochrome_static_initializers

It would really be great if we could consolidate as much of these scripts as possible.