The profile chooser menu, also known as the avatar menu, is represented by different, platform-dependent views and models. The AvatarMenu class is used to retrieve items for the menu and responds to actions like switching, adding and editing profiles.
AvatarMenu defines the Item struct and provides methods for retrieving these items and interacting with an item's associated profile. Most of its functions delegate tasks to either the ProfileList object or the AvatarMenuActions object, both of which are created in AvatarMenu::AvatarMenu(). The various Views use AvatarMenu to determine whether the menu should be shown, to access the menu items, and to respond to clicks on menu items or links.
AvatarMenu delegates generation of the profile list to the ProfileList interface, which currently has two implementations. On desktop Chrome, ProfileListDesktop simply exposes all of the profiles in LocalState for inclusion in the menu. ProfileListChromeOS restricts the listed profiles to those that are associated with logged-in users, hiding the Default profile and profiles for users who are not logged into the session (including managed users); additionally, the menu items' icon fields are populated with user images instead of profile avatar icons. Both implementations rely on the ProfileInfoInterface (ProfileInfoCache), and ProfileListChromeOS also uses UserManager.
The AvatarMenuActions interface controls behavior such as adding and editing profiles, as well as determining whether these links should be shown. As of this writing, AvatarMenuActionsDesktop allows for adding and editing profiles through the Settings sub-page, as well as signing out of a profile, while AvatarMenuActionsChromeOS disallows editing (i.e., returns false from ShouldShowEditProfileLink) and only lets the Add Profile link be shown if the right conditions are met with respect to the user's type and other users on the machine. Currently, AvatarMenuActions implementations use the Browser object; in the future, this dependency should be removed by delegating actions like AddNewProfile and EditProfile.