Roll engine e73c9c8f6bd5..7b968ff95ff1 (3 commits) (#44158)

git@github.com:flutter/engine.git/compare/e73c9c8f6bd5...7b968ff95ff1

git log e73c9c8f6bd5..7b968ff95ff1 --no-merges --oneline
2019-11-05 chinmaygarde@google.com Ensure that the CAMetalLayer FBO attachments can be read from. (flutter/engine#13643)
2019-11-04 47866232+chunhtai@users.noreply.github.com Revert "Added new lifecycle enum (#11913)" (flutter/engine#13632)
2019-11-04 47866232+chunhtai@users.noreply.github.com Added new lifecycle enum (flutter/engine#11913)


If this roll has caused a breakage, revert this CL and stop the roller
using the controls here:
https://autoroll.skia.org/r/flutter-engine-flutter-autoroll
Please CC cbracken@google.com on the revert to ensure that a human
is aware of the problem.

To report a problem with the AutoRoller itself, please file a bug:
https://bugs.chromium.org/p/skia/issues/entry?template=Autoroller+Bug

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

bin/internal/engine.version

-e73c9c8f6bd5876f1d95df98ec47a36a00776148
+7b968ff95ff17ac798dedb46272ebb258738fbc6