KeyedService is a layered component (https://sites.google.com/a/chromium.org/dev/developers/design-documents/layered-components-design) to enable it to be shared cleanly on iOS.
This component has the following structure:
- core/: shared code that does not depend on src/content/ or src/ios/ - content/: Code based on the content layer. - ios/: Code based on src/ios.