git@github.com:flutter/engine.git/compare/c43739ba53ce...51bdf834203c

git log c43739ba53ce..51bdf834203c --no-merges --oneline
2019-08-21 chinmaygarde@google.com Migrate Embedder API documentation to Doxygen format. (flutter/engine#11255)
2019-08-21 iska.kaushik@gmail.com Do not add null task observers (flutter/engine#11315)
2019-08-21 chinmaygarde@google.com When using a custom compositor, ensure the root canvas is flushed. (flutter/engine#11310)
2019-08-20 franciscojma86@gmail.com [glfw] Send the glfw key data to the framework. (flutter/engine#9386)

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 (liyuqian@google.com), and stop
the roller if necessary.