Upgrading Engine's Android API version

When new Android versions become available, the following steps should be taken in order to fully support the new API version in the Flutter Engine. These steps only change the Engine to build against and target the new API and does not guarantee everything works with the changes in the new android API.

Buildroot:

build/config/android/config.gni: Edit default_android_sdk_version and default_android_sdk_build_tools_version

SDK and other dependencies:

Flutter now includes a script to download, package, and upload the Android SDK to CIPD. These CIPD packages are then used as dependencies by the Flutter engine and recipes so that there is a stable archived version of the Android SDK to depend on. The script is located in the Flutter engine repo under tools/android-sdk/create_cipd_packages.sh.

Edit tools/android-sdk/packages.txt to refer to the updated versions you want. The format for each line in packages.txt is <package_name>:<subdirectory_to_upload>. Typically, each <package_name> should be updated to the latest available version which can be found with the sdkmanager --list --include_obsolete. sdkmanager can be found in your commandline-tools package of the android sdk.

The script must be run on a Linux or Mac host. Run:

`$ ./tools/android-sdk/create_cipd_packages.sh <new_version_tag> <path_to_your_local_android_sdk>`

This script will download and re-upload the entire SDK, so it may take a long time to complete. cmdline-tools should be installed in your local sdk as the script uses sdkmanager. Once the CIPD packages are finished uploading, you can update the sdk version tag used in .ci.yaml, DEPS, and elsewhere.

It is no longer recommended to upload CIPD android sdk packages manually, but if it must be done, run the following commands to zip and upload each package to CIPD:

`$ cipd create -in <your-android-dir>/Android/sdk/<some_package> -name flutter/android/sdk/<some_package> -tag version:<new-version-tag>`

Typically, <your-android-dir> is in your home directory under ~/Library/Android. The <new-version-tag> is what you will use to specify the new package you uploaded in the Flutter engine DEPS file.

Engine:

• DEPS: Roll buildroot hash
• DEPS: Change the version parameter under flutter/android/sdk/all/${{platform}} to the newly uploaded CIPD version tag. Eg, 'version': 'version:30r2'
• Change any references to the old SDK version to the latest in build.gradle across the repo.
• In tools/javadoc/gen_javadoc.py, bump the reference to android-XX in classpath to the latest version.
• In tools/cipd/android_embedding_bundle/build.gradle, bump compileSdkVersion XX to the latest version.
• In shell/platform/android/test_runner/build.gradle, bump compileSdkVersion XX to the latest version.
• In all android projects in testing, upgrade the compileSdkVersion and targetSdkVersion in android/app/build.gradle.

Flutter LUCI Recipes:

Scenario tests recipes/engine/scenarios.py: Update the CIPD hash to the latest version that contains the configuration for the Android Virtual Device (AVD) desired generic_android<API#>.textpb and change the script to use the new textpb config and change the API number in the logs. The CIPD package for the AVD launcher can be found at https://chrome-infra-packages.appspot.com/p/chromium/tools/android/avd/+/ and updating the packages uploaded there is tracked in https://bugs.chromium.org/p/chromium/issues/detail?id=1112429#c7

Framework, examples and samples

• Templates in tooling: Change targetSdkVersion in various build.gradle.tmpl files to use the new API version
• Examples, samples, gallery, etc: Change targetSdkVersion in android/app/build.gradle for each project to the new API version.