Android Studio doesn't recognize InstanceID class
Update your Play services SDK to
compile 'com.google.android.gms:play-services:7.5.0'
Then clean your Project.
Worked for me. Hope it works for you too!
you are missing the gcm
add on your gradle:
compile "com.google.android.gms:play-services-gcm:10.2.6"
Basically, you have to use the latest version of the Google Play Services, Android Support Repository and Google Repository for this to work, and then include the latest version of the Google Play Services
compile 'com.google.android.gms:play-services:7.5.0'