Check for a binary callback first since a function with an optional
second argument will match both typedefs.

Remove documentation around a synchronous error following some other
error or value - a synchronous error can never follow a value or an
asynchronous error. If there is a synchronous error it will _always_ be
the first thing to happen.

Add a test for a unary error handler and an error handler with an
optional stack trace argument.

* Separate DropdownButtonFormField and DropdownButton test files

The environment variable for all desktop platforms is currently
ENABLE_FLUTTER_DESKTOP to allow backward compatibility with existing
workflows. However, this is actually causing issues since 'flutter
config' provides a better experience (most importantly, IDEs will work
correctly, which is generally not the case with the environemnt
variable). Currently people following old (third-patry) instructions
don't realize that they are missing available functionality, so aren't
looking for the current instructions.

In adddition, this will be confusing as different platform graduate to
channels other than master at different times.

To resolve both issues, the environment variable fallback is now
separate for each desktop platform, and follows a naming scheme
consistent with the web environment variable.

* Add onLongPress to Buttons.

* Button enabled status will now respond to onLongPress

git@github.com:flutter/engine.git/compare/419f5d594afc...46c757be07fd

git log 419f5d594afc..46c757be07fd --no-merges --oneline
2019-10-29 iska.kaushik@gmail.com [dart_runner] Common libs need to exist for aot runner (flutter/engine#13419)
2019-10-29 jason-simmons@users.noreply.github.com Fix the dry run mode of the GN format checker script (flutter/engine#13406)
2019-10-29 jason-simmons@users.noreply.github.com Reformat BUILD.gn files to comply with the format checker presubmit script (flutter/engine#13401)
2019-10-29 jason-simmons@users.noreply.github.com Use DartExecutor.getBinaryMessenger in FlutterNativeView instead of deprecated send methods (flutter/engine#13403)
2019-10-29 bkonyi@google.com Roll src/third_party/dart e1fce75301..0b96f9f9ae (28 commits)
2019-10-29 matthew-carroll@users.noreply.github.com Converted ActivityAware and ServiceAware Lifecycles to opaque objects (#43670) (flutter/engine#13402)


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

This re-lands the change that adds focus nodes, hover, and shortcuts to switches, checkboxes, and radio buttons. (#43213), with fixes for the web tests that weren't enabled in the master that it was synced to when I first landed it.

* Update README to include non-mobile targets

* Tweak headings

* Adjust and refactor all MaterialButton tests into its respective file

This is to account for the flutter_runner migration.
fxb/fl-250 has more context. This change specifically uses
the build rules that were added as a part of: fxr/333681

This reverts commit b9eb3f71.

We fixed the issue by updating the constructors.

Drag from the right is no more
Longpress is now only 100ms instead of 500
Added optional duration field to longpressgesturerecognizer
Added controller field to material scrollbar api
Haptic feedback only triggers when scrollbar is fully expanded
Added haptic feedback when releasing the scrollbar after dragging it

419f5d594 Roll src/third_party/skia 1beb8ae9a2f5..f22dda960136 (11 commits) (flutter/engine#13409) (#43698)


git@github.com:flutter/engine.git/compare/25563a12cab1...419f5d594afc

git log 25563a12cab1..419f5d594afc --no-merges --oneline
2019-10-29 skia-flutter-autoroll@skia.org Roll src/third_party/skia 1beb8ae9a2f5..f22dda960136 (11 commits) (flutter/engine#13409)


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 aaclarke@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

git@github.com:flutter/engine.git/compare/49971e21402e...25563a12cab1

git log 49971e21402e..25563a12cab1 --no-merges --oneline
2019-10-29 iska.kaushik@gmail.com Update recipe_changelog to account for dart_aot runner and clobbering
2019-10-28 iska.kaushik@gmail.com Revert "[flutter_runner] Don't build far files twice (#13397)" (flutter/engine#13400)
2019-10-28 matthew-carroll@users.noreply.github.com Remove multiplexed Flutter Android Lifecycle. (#43663) (flutter/engine#13394)
2019-10-28 iska.kaushik@gmail.com [flutter_runner] Don't build far files twice (flutter/engine#13397)
2019-10-28 chinmaygarde@google.com Delay metal drawable acquisition till frame submission. (flutter/engine#13367)
2019-10-28 skia-flutter-autoroll@skia.org Roll fuchsia/sdk/core/mac-amd64 from 9MM-e... to mc3jR... (flutter/engine#13390)
2019-10-28 bkonyi@google.com Roll src/third_party/dart 5e39817ec7..e1fce75301 (2 commits)


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 aaclarke@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

git@github.com:flutter/engine.git/compare/c3b63d610b07...49971e21402e

git log c3b63d610b07..49971e21402e --no-merges --oneline
2019-10-28 yjbanov@google.com Implement basic Picture.toImage via BitmapCanvas (flutter/engine#13391)
2019-10-28 chinmaygarde@google.com Switch the MacOS Desktop embedder to using a thread configuration where the platform and render task runners are the same. (flutter/engine#13300)
2019-10-28 skia-flutter-autoroll@skia.org Roll src/third_party/skia 18f5b1a6dd77..1beb8ae9a2f5 (9 commits) (flutter/engine#13392)


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 aaclarke@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

* Added note about design doc template.

* switched "our" to "flutter"

* updated link

* Fix device lab tests

* Migrate examples to the Android embedding v2 (#43221)