We are severely resource constrained on the tryjobs. This is hindering progress on ToT due to scheduling failures and rate limits. There are no plans to requisition more resources in this infra scheme as the migration to tryjobs on LUCI is the preferred way forward. This patch removes presubmits that are somewhat redundant. Each removed presubmit and the justification is given below:
* `build_and_test_linux_opt_release`: The AOT variant is tested by `build_and_test_linux_opt_profile` (actually its replacement, see the next point).
* `build_and_test_linux_opt_profile`: When we build the host profile variant for Android, we test it as well instead of building the extra variant (since we already need a host for a target build).
* `build_and_test_android_unopt_debug`: `gen_javadoc` have been moved to the profile variant. `Roboelectric` tests have been moved to profile variant. JIT infra will be tested by the the host tests.
* ToT framework checks: These will be performed (by the autoroller)[https://autoroll.skia.org/r/flutter-engine-flutter-autoroll?tab=status] which also has a sheriff rotation. This will also avoid us having to ignore red presubmits on manual changes.
Everything else is left as-is. To be clear, this causes strictly less checks to be performed on each commit.
`gclient sync` now grabs Robolectric, JUnit, and their transitive
runtime dependencies. They're being stored in a new CIPD package,
`flutter/android/robolectric_bundle`.
`shell/platform/android/BUILD.gn` has a new target for building the
tests, `robolectric_tests`. `testing/run_tests.py` has been extended to
build and run the new target. Runs the android tests under
"build_and_test_android" on CI.
This also adds some very simple sample tests to start with and a README
to the java tests directory.
This is in preparation for the tryjobs to run these tests. The LUCI harness will also be updated so that the tests to run are specified in the repo instead of the recipe.
Sample usage:
To run only the embedder_unittests in the engine with the profile variant, the command would be
```
./flutter/testing/run_tests.py --variant host_profile_unopt --type engine --filter embedder_unittests
``
To run only the geometry in Dart with the debug variant, the command would be
```
./flutter/testing/run_tests.py --variant host_debug_unopt --type dart --filter geometry_test
``
Without any argument, the behavior is identical to `run_tests.sh`.
In a subsequent patch, I will enable running unit-tests on Windows in the tryjobs. The lack of compatibility of the shell script on Windows made it so that we never ran any Windows unit-tests in the tryjobs.
