Bug Fixes
- analytics: allow manual tracking of ad_impression (931468a), closes #6307 #6312
- android: specify that android services are not exported (39e0444), closes /github.com/firebase/firebase-android-sdk/blob/ad135d8c3c1243b4c673e17bc032ee1052fb2a22/firebase-common/src/main/AndroidManifest.xml#L10-L12