Cronet build instructions

[TOC]

Checking out the code

Follow all the Get the Code instructions for your target platform up to and including running hooks.

Building Cronet for development and debugging

Note: These instructions are for standard CLI environments. If you are using a managed environment (e.g., Cider-V), please follow the platform-specific build workflows instead of running these commands directly.

Similarly to Chromium, to build Cronet for development and debugging purposes:

1. Use gn to create ninja files targeting the intended platform
2. Use ninja to execute the ninja files to run the build

The two main difference from a Chromium build are:

1. Cronet only builds a subset of Chromium
2. Cronet uses a different set of gn args to build

Using gn

TODO(crbug.com/40287068): This might change in the future. Remembering the set of gn args to be used for a Cronet build is complicated. So, we rely on //components/cronet/tools/cr_cronet.py to do that for us.

$ ./components/cronet/tools/cr_cronet.py gn

By default, this generates the build configuration in out/Debug-arm64. To better understand how this works, and the configuration parameters it supports (e.g., --release, --x64, --asan), refer to cr_cronet.py's source code and:

$ ./components/cronet/tools/cr_cronet.py --help

Using ninja

The previous steps generated the files needed to compile Cronet. All that remains now is to find a target to build. This can be done through this command:

$ autoninja -C <out_dir> <target>

Where <out_dir> is what was set through cr_cronet.py (e.g., out/Debug-arm64) and <target> is one of of Cronet's target within some BUILD.gn file:

• cronet_package: The complete Cronet library for Android. Artifacts land in <out_dir>/cronet/ (native libraries under libs/).
• cronet_sample_apk: The demonstration app. APK at <out_dir>/apks/CronetSample.apk.
• cronet_test_instrumentation_apk: The Android test suite. APK at <out_dir>/apks/CronetTestInstrumentation.apk.
• net_unittests: Core Chromium network stack C++ unit tests. Native executable at <out_dir>/net_unittests.

Building Cronet mobile for releases

To build Cronet with optimizations and with debug information stripped out:

$ gn clean <out_dir>
$ ./components/cronet/tools/cr_cronet.py gn --release
$ autoninja -C <out_dir> cronet_package

Default release output directory is out/Release-arm64.