Checking out and building Cronet for Android

Checking out the code

Follow all the Checking out and building Chromium for Android instructions up to and including the Run the hooks step.

Building Cronet

Building Cronet for development and debugging

To build Cronet for development and debugging purposes:

$ ./components/cronet/tools/ gn
$ ninja -C out/Debug cronet_package

Note: these commands clobber output of previously executed gn commands in out/Debug.

Building Cronet for releases

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

$ ./components/cronet/tools/ -r gn 
$ ninja -C out/Release cronet_package

Note: these commands clobber output of previously executed gn commands in out/Release.

Building for other architectures

By default ARMv7 32-bit executables are generated. To generate executables targeting other architectures modify's gn_args variable to include:

  • For ARMv6 32-bit: arm_version=6
  • For ARMv8 64-bit: target_cpu="arm64"
  • For x86 32-bit: target_cpu="x86"
  • For x86 64-bit: target_cpu="x64"
  • For MIPS: target_cpu="mipsel"

Running tests

Running tests locally

First, connect an Android device by following the Plug in your Android device steps. Prefer using a device running a userdebug build.

Running Cronet Java unit tests

To run Java unit tests that actuate the Cronet API:

$ ./components/cronet/tools/ gn
$ ./components/cronet/tools/ build-test

To run particular tests specify the test class and method name to the build-test command. For example:

$ ./components/cronet/tools/ build-test -f QuicTest#testQuicLoadUrl

Running net_unittests and cronet_unittests

To run C++ and Java unit tests of net/ functionality:

$ ./components/cronet/tools/ gn
$ ninja -C out/Debug net_unittests
$ ./out/Debug/bin/run_net_unittests --fast-local-dev

For more information about running net_unittests, read Android Test Instructions.

There are a small number of C++ Cronet unit tests, called cronet_unittests, that can be run by following the above instructions and substituting cronet_unittests for net_unittests.

Running Cronet performance tests

To run Cronet's perf tests, follow the instructions in components/cronet/android/test/javaperftests/

Running tests remotely

Once you've uploaded a Chromium change list using git cl upload, you can launch a bot to build and test your change list:

$ git cl try -b android_cronet_tester

This will run both the Cronet Java unit tests and net_unittests.


Debug Log

Messages from native (C++) code appear in the Android system log accessible with adb logcat. By default you will see only messages designated as FATAL. To enable more verbosity:

See VLOG(1) and VLOG(2) logging:

$ adb shell setprop log.tag.CronetUrlRequestContext VERBOSE

See VLOG(1) logging:

$ adb shell setprop log.tag.CronetUrlRequestContext DEBUG 

See NO (only FATAL) logging:

$ adb shell setprop log.tag.CronetUrlRequestContext NONE

Network Log

NetLog is Chromium's network logging system. To create a NetLog dump, you can use the following pair of methods:


Unlike the Android system log which is line-based, the Chromium log is formatted in JSON. As such, it will probably not be well-formed until you have called the stopNetLog() method, as filesystem buffers will not have been flushed.

Retrieve the file from your device's file system, and import it to chrome browser at chrome://net-internals/#import, or which helps to visualize the data.

Symbolicating crash stacks

If an app or test using Cronet crashes it can be useful to know the functions and line numbers involved in the stack trace. This can be done using the Android system log:

$ ./components/cronet/tools/ stack

Or using tombstones left behind after crashes:

$ CHROMIUM_OUTPUT_DIR=out/Debug ./build/android/