Chrome 51 Beta (the latest version of Chrome) supports the Credential Management API. The API is a standards-track API proposed by W3C and grants developers programmatic access to a browser's credential manager which streamlines the sign-in process. Through Chrome support for the API, Google aims to lower the need for creating, remembering and typing passwords as users engage with various websites.
In the Chrome implementation, Chrome's password manager stores user credentials. Once a user is singed into Chrome, the user can sync passwords across devices. Synced passwords can also be shared with Android apps that utilize the Smart Lock for Passwords API. While the API certainly increases ease of use, Google readily acknowledges using the API creates a security risk.
At a high level, the Credential Management API allows developers to store and retrieve password credentials and federated credentials. The API provides three functions (i.e. get, store, requireUserMediation). After integration, the API allows users to sign in with a single tap, remember the federated account a user has previously signed in with, and sign users back in after session expiration.