Following the commands to dump sql files (version_77.sql etc.)
https://cs.chromium.org/chromium/src/components/webdata/common/web_database_migration_unittest.cc?rcl=39ecd6dafc529a41b2a219b6eed1d7da4030eff5&l=122

The presence of payment_method_manifest and web_app_manifest_section tables is shown in the dump, but not in web_database_migration_unittest.

I believe part of the solution is to add the new tables here:

https://cs.chromium.org/chromium/src/components/webdata/common/web_database_migration_unittest.cc?rcl=39ecd6dafc529a41b2a219b6eed1d7da4030eff5&l=68

But I haven't investigated fully. It will affect the next person wanting to write a migration though, since the SQL can't be generated cleanly.