Fast Checkout Android Feature

This folder contains the internal parts of the Fast Checkout component. Files, classes and methods defined in here are not meant to be used outside of this package.

This document provides a brief overview of the architecture.

Component structure

This component follows the typical MVC structure that is widely used in Chrome on Android. The MVC structures separates logic from representation:

• The controller creates and connects all subcomponents and performs logic that affects the visual appearance of the component.
• The model keeps all state that affects the visual appearance of the component. Changes made to it are automatically propagated to the view by a Model-Change-Processor (MCP) as defined in //src/ui/android/java/src/org/chromium/ui/modelutil/
• The view is the representation of the component. It enforces styles and is mostly called by a view binder to set mutable properties.

A typical request to the Fast Checkout component API that intends to change the visible appearance involves all component parts. For example if the API caller requests to show new options:

1. The API caller asks the controller to show a set of autofill profiles and credit cards.
   1. The controller prepares and filters the options for display.
   2. The controller writes the prepared options into the model.
2. The MCP picks up model changes.
   1. The MCP identifies that the AUTOFILL_PROFILE_LIST and CREDIT_CARD_LIST properties were changed.
   2. The MCP uses a ViewBinder to bind each changed option to the corresponding view (e.g. a TextView inside a LinearLayout).
3. The view renders the corresponding UI.
   1. The view may apply style, RTL settings and event handlers for click events.