Cannot resolve symbol 'Auth' for google integration in android studio

I had the same issue, add compile 'com.google.android.gms:play-services-auth:10.0.1 (your project's latest version) in your app level gradle file.

Add the dependencies for Firebase Authentication and Google Sign-In to your app-level build.gradle file:

compile 'com.google.firebase:firebase-auth:10.0.1'
compile 'com.google.android.gms:play-services-auth:10.0.1'

• Put apply plugin: 'com.google.gms.google-services' beneath apply plugin: 'com.android.application'.

• Add compile 'com.google.android.gms:play-services-auth:8.3.0' inside dependencies block. This will add related dependencies to your project.

With the latest version (2.2.2) what I had to do in order to fix this issue was to add the line below as a dependency into my app/build.gradle file

compile 'com.google.android.gms:play-services-auth:9.8.0'

Hope it helps.