Roll engine 5d3012a1bb9d..cf6648313df8 (2 commits) (#38638)

git@github.com:flutter/engine.git/compare/5d3012a1bb9d...cf6648313df8

git log 5d3012a1bb9d..cf6648313df8 --no-merges --oneline
2019-08-15 jason-simmons@users.noreply.github.com Remove the output directory prefix from the Android engine JAR filename (flutter/engine#11015)
2019-08-15 inthroxify@users.noreply.github.com Fix flutter/flutter #34791 (flutter/engine#9977)

The AutoRoll server is located here: https://autoroll.skia.org/r/flutter-engine-flutter-autoroll

Documentation for the AutoRoller is here:
https://skia.googlesource.com/buildbot/+/master/autoroll/README.md

If the roll is causing failures, please contact the current sheriff (stuartmorgan@google.com), and stop
the roller if necessary.

bin/internal/engine.version

-5d3012a1bb9dc2204eaa1bef1fef01f5484c3a57
+cf6648313df81678cbdc6626f80220eb11250ca9