Release 5.21.0

• Add custom views to In-App Checkout with a checkout extension.
• Prefix layout resources to avoid collision

Release 5.20.0

• NEW! Customize In-App Checkout with Checkout Extensions
• Minor bug fixes and improvements

Release 5.19.0

• Purchase tracking improvements in the embedded browser
• The embedded browser no longer intermittently opens search results in a dialog window
• Install sheet optimizations

Release 5.18.0

• Adds support for app install banners using Chrome Intents for Android.
• Bug fixes and improvements to authorization challenge flow.
• Bug fixes and improvements to web view used for in-app checkout.

Release 5.17.0

• Deprecates Button#stop() since it can lead to unexpected behavior when called externally. Apps should use Button#logout() instead.
• Deprecates ButtonDropin#prepareForDisplay(ButtonContext) and ButtonDropin#prepareForDisplay(ButtonContext, ButtonDropin.Listener). Apps should use ButtonDropin#prepareWithAction(AppAction) instead.
• Minor bug fixes and improvements to app install flow.

Release 5.16.0

• Fixes web checkout bug that opened the Google Play store in a popup window instead of the native app for some websites when clicking an app install banner.
• Fixes app install notification bug when using SSO authentication.
• Minor networking improvements and enhanced debug logging when fetching app actions.

Release 5.15.0

• Adds single sign-on merchant (SSO) authorization challenge
• In-app checkout bug fixes and improvements

Release 5.14.0

• Adds support for Android Oreo (API 26)
• Adds ability to register a callback for MerchantAction completion

Release 5.13.1

• Enables SUBA

Release 5.13.0

• Improvements to navigation in web checkout flow
• Fixes issue with Facebook login in web checkout flow