General hierarchy of UI elements in authentication UI:

LockScreen is the root element, that owns LockContentsView (potentially wrapped in LockDebugView). It resides in kShellWindowId_LockScreenContainer layer of the primary display.

LoginDataDispatcher implements LoginScreenModel and redirects calls to its observers, main of which is LockContentView.

LockContentView is a full-screen view that owns and displays all other authentication UI elements:

• When only one user is in the list it is displayed using LoginBigUserView;
• When two users are on the list, they are displayed using two LoginBigUserViews;
• When 3+ users are in the list, one LoginBigUserView is used to display selected user, and rest of the users are displayed using ScrollableUsersListView;
• LoginExpandedPublicAccountView when the user tries to sign in to public account.
  • Allows selection of language/keyboard for Public session
  • Displays monitoring warning indicator and triggers PublicAccountWarningDialog
  • Allows to actually sign in to the public account
• Also owns/refers to following optional UI elements:
  • LockScreenMediaControlsView
  • NoteActionLaunchButton
  • UI that shows information about system.
  • Various bubbles and indicators
    • UserAddingScreenIndicator displayed when screen is used for multiprofile login
    • BottomStatusIndicator for indicating management/ADB sideloading info
    • ManagementBubble for management disclosure
    • AuthErrorBubble for displaying auth errors
    • LoginErrorBubble for displaying:
      • security warnings when detachable keyboard does not match one used on previous login
      • ext4 migration warning
      • supervised user deprecation notice
    • LoginTooltipView for easy unlock tooltips

LoginBigUserView contains one of:

• LoginPublicAccountUserView that consists of:
  • LoginUserView (see below)
  • Arrow button to proceed to showing LoginExpandedPublicAccountView (see above)
• LoginAuthUserView that represents user information and provides UI for authentication. It consists of:
  • LoginUserView
    • (Animated) user image
    • Name label
    • Drop-down info with an option to remove user
  • LoginPasswordView that shows:
    • Password input field
    • “Show Password” button
    • CAPS LOCK indicator
    • Submit button
    • Quick unlock indicator
  • or pair of LoginPinView (that provides digital keyboard) along with LoginPinInputView (that provides positional input field)
  • Password/PIN toggle button
  • Button to trigger online sign-in
  • FingerprintView
  • ChallengeResponseView
  • DisabledAuthMessageView (e.g. when child user has an associated time limit)
  • LockedTpmMessageView

PinRequestWidget works as a standalone UI. It contains a PinRequestView that consists of LoginPinKeyboard and one of either FixedLengthCodeInput or FlexCodeInput, both of which are subclasses of AccessCodeInput.