Updating the Embedding Dependencies

The instructions in this README explain how to create a CIPD package that contains the build-time dependencies of the Android embedding of the Engine, and the dependencies of the in-tree testing framework. The Android embedder is shipped to Flutter end-users, but these build-time dependencies are not. Therefore, the license script can skip over the destination of the CIPD package in an Engine checkout at src/flutter/third_party/android_embedding_dependencies. Even so, the CIPD package should contain a LICENSE file, and the instructions below explain how to fetch the license information for the dependencies.

Requirements

1. If you have a flutter/engine checkout, then you should already have Depot tools on your path.
2. You should have a copy of gradle in a flutter/engine checkout under src/third_party/gradle/bin/gradle.

Steps

1. Update src/flutter/tools/androidx/files.json. (This file includes the Maven dependencies used to build Flutter apps).
2. cd into this directory: src/flutter/tools/cipd/android_embedding_bundle.
3. Run gradle downloadLicenses
4. Run gradle updateDependencies
5. Examine the file ./build/reports/license/license-dependency.xml. If it contains licenses other than "The Apache License, Version 2.0" or something very similar, STOP. Ask Hixie for adivce on how to proceed.
6. Copy or move the lib/ directory to src/flutter/third_party/android_embedding_dependencies/, overwriting its contents, and ensure the Android build still works.
7. Run cipd create --pkg-def cipd.yaml -tag last_updated:"$version_tag" where $version_tag is the output of date +%Y-%m-%dT%T%z.
8. Update the DEPS file entry for android_embedding_dependencies with the new tag: last_updated:"$version_tag".
9. Update the GN list embedding_dependencies_jars in src/flutter/shell/platform/android/BUILD.gn.
10. The Gradle lockfiles will need to be updated, but they cannot be updated in this PR. They will need to be updated in a follow-up PR. Instead run <repo_root>/dev/tools/bin/generate_gradle_lockfiles.dart --no-gradle-generation --no-exclusion --ignore-locking=Reason: <ISSUE>. Replace <ISSUE> with a link to an issue. This will create a '.ignore-locking.md' file that will disable Grdle locking and allow tests to pass without locking.
11. Once the initial PR is submitted, you will need to create a follow-up PR that updates the Gradle lockfiles and deletes the ignore file. Run <repo_root>/dev/tools/bin/generate_gradle_lockfiles.dart --no-gradle-generation --no-exclusion --stop-ignoring to delete the ignore file and update the Gradle lockfiles. Submit this PR as well.