org.chromium.base.Log methods support printf-style formatting, specifically to avoid doing unnecessary string concatentation, but many callsites don't use it and still just concatenate the string at the callsite. Proguard can't eliminate this code, even when inside Log.d() - it doesn't realise that the StringBuilder calls have no useful effect, so we end up building the entire string even for debug logging that's never printed at all.

We should maybe have a presubmit script that bans this, as it will reduce binary size a bit. We should probably also ban android.util.Log as this doesn't have the same features and is still used in some cases.