Chromium on Chromium OS is built from a mix of code sourced from Chromium on Linux and Chromium on Windows. Much of the user interface code is shared with Chromium on Windows.
If you make changes to Chromium on Windows, they may affect Chromium on Chromium OS. Fortunately to test the effects of your changes you don't need to build all of Chromium OS, you can just build Chromium for Chromium OS directly on Linux.
First, follow the normal Linux build instructions as usual to get a Chromium checkout.
If you plan to test the Chromium build on your dev machine and not a Chromium OS device, run the following in your chromium checkout:
$ gn gen out/Default --args='target_os="chromeos"' $ ninja -C out/Default -j32
NOTE: You may wish to replace ‘Default’ with something like ‘Cros’ if you switch back and forth between Linux and Chromium OS builds, or ‘Debug’ if you want to differentiate between Debug and Release builds (see below) or DebugCros or whatever you like.
NOTE: If using goma increase -j32 (which controls parallelization) to something higher, 500 or 1000. Consider adding
-l20 which prevents ninja from starting jobs if the load average is too high - this prevents system hangs when using -j1000 when goma is down.
See GN Build Configuration for more information about configuring your build.
Some additional options you may wish to set by passing in
gn gen or running
gn args out/Default:
is_component_build = true use_goma = true is_debug = false # Release build, significantly faster dcheck_always_on = true # Enable DCHECK (with is_debug = false) # Set the following true to create a Chrome (instead of Chromium) build. is_official_build = false is_chrome_branded = false
The Chromium OS build requires a functioning GL so if you plan on testing it through Chromium Remote Desktop you might face drawing problems (e.g. Aura window not painting anything). Possible remedies:
--use-gl=osmesa, but it‘s ultra slow, and you’ll have to build osmesa yourself.
To more closely match the UI used on devices, you can install fonts used by Chrome OS, such as Roboto, on your Linux distro.
To specify a logged in user:
--user-data-dir=/tmp/chrome --bwsi --incognito --login-user='$guest' --login-profile=user
Signing in as a specific user is useful for debugging features like sync that require a logged in user.
See Building Chromium for a Chromium OS device for information about building and testing chromium for Chromium OS.