Documentation Fix to FM.RemoteMessage.getMessageId

[spundun]

Current documentation refers to a side effect of our (now discontinued) delivery-receipt behavior, some customers have started to rely on it.

[google-oss-bot]

Coverage Report ¹

Affected Products

No changes between base commit (ea9775b) and merge commit (02b0cd7).

Test Logs

• Base (ea9775b): https://android-ci.firebaseopensource.com/view/gcs/android-ci/logs/postsubmit-check-coverage/1490717015915106304
• Merge (02b0cd7): https://android-ci.firebaseopensource.com/view/gcs/android-ci/pr-logs/pull/firebase_firebase-android-sdk/3419/check-coverage-changed/1490842982935433221

Notes

• Commit (02b0cd7) is created by Prow via merging PR base commit (ea9775b) and head commit (011e382).
• Run gradle <product>:checkCoverage to produce HTML coverage reports locally. After gradle commands finished, report files can be found under <product-build-dir>/reports/jacoco/.

1. https://storage.googleapis.com/firebase-sdk-metric-reports/iQEIHPw6M8.html

[google-oss-bot]

Size Report ¹

Affected Products

No changes between base commit (ea9775b) and merge commit (02b0cd7).

Test Logs

• Base (ea9775b): https://android-ci.firebaseopensource.com/view/gcs/android-ci/logs/postsubmit-binary-size/1490717015902523395
• Merge (02b0cd7): https://android-ci.firebaseopensource.com/view/gcs/android-ci/pr-logs/pull/firebase_firebase-android-sdk/3419/binary-size/1490842982935433222

Notes

• Commit (02b0cd7) is created by Prow via merging PR base commit (ea9775b) and head commit (011e382).

1. https://storage.googleapis.com/firebase-sdk-metric-reports/bGx3Jyz1kJ.html