Upgrading to FirebaseUI 2.0

• Facebook and Twitter dependencies - FirebaseUI no longer directly depends on the Facebook or Twitter SDKs. If you plan to enable either of these providers you should include the appropriate SDK in your app to avoid a crash. This saves space for developers only using Google/Email/Phone authentication.
• Sign out and delete - The AuthUI#delete(Activity) and AuthUI#signOut(Activity) methods have been removed, please use the versions that accept FragmentActivity.
• Error codes - ResultCodes.RESULT_NO_NETWORK has been removed. Instead you should use IdpResponse.fromResultIntent(data) to get the response from the AuthUI intent and then check if IdpResponse#getErrorCode() is ErrorCodes.NO_NETWORK.
• Choosing providers - setProviders has been deprecated, please use setAvailableProviders which now respects the order in which you provide them. The varargs version of setProviders has been removed completely.
• Facebook and Google scopes - setting scopes via string resources is no longer supported, please set scopes in code using IdpConfig.
• Themes - AppCompat theme properties such as colorPrimary and colorAccent are now used to style FirebaseUI automatically without any need for customization. Unless your auth UI needs a different theme than the rest of your app, please remove AuthUI.SignInIntentBuilder#setTheme(int) and its related xml theme from your auth intent builder and check to make sure that the auth UI has been themed correctly.
• Smart Lock for passwords - setIsSmartLockEnabled has added a two-argument overload. There are now separate flags for enabling the hint select and enabling the saving/retrieving of full credentials from the API. Setting the same value for each flag will emulate the previous single-flag behavior.

• Change events - the signature of ChangeEventListener#onChildChanged has been modified to include a DataSnapshot argument.
• Snapshot parsing - the parseSnapshot method of the adapters has been removed. Instead, you should pass a custom SnapshotParser to the adapter constructor.
• Method visibility - the onDataChanged method has changed from protected to public, which will require a change in your code if you are overriding this method.

No breaking changes.