This directory should contain Chrome OS specific code that has //chrome dependencies.
This directory is for shared code between Ash and Lacros. Code that is only used by Lacros should be in chrome/browser/lacros/ and code that is only used by Ash should be in chrome/browser/ash/.
There are a few exceptions to the above rules while the code is being migrated, e.g. c/b/c/exceptions/ and c/b/c/fileapi/ which are being actively worked on to separate platform-specific code to the proper directories. See the “Lacros: ChromeOS source code directory migration” design doc at https://docs.google.com/document/d/1g-98HpzA8XcoGBWUv1gQNr4rbnD5yfvbtYZyPDDbkaE.