Mojo is an effort to extract a common platform out of Chrome's renderer and plugin processes that can support multiple types of sandboxed content, such as HTML, Pepper, or NaCl.
The instructions below only need to be done once. Note that a simple "git clone" command is not sufficient to build the source code because this repo uses the gclient command from depot_tools to manage most third party dependencies.
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Download depot_tools and make sure it is in your path:
http://www.chromium.org/developers/how-tos/install-depot-tools -
Create a directory somewhere for your checkout, cd into it, and run the following commands:
$ fetch mojo # use --target_os=android if you want an Android build.
$ cd src
$ ./build/install-build-deps.sh
$ gn gen out/Debug
The "fetch mojo" command does the following:
- creates a directory called 'src' under your checkout directory
- clones the repository using git clone
- clones dependencies with gclient sync
Finally, "install-build-deps.sh" installs any packages needed to build.
If the fetch command fails, you will need to delete the src directory and start over.
Build Mojo by running:
$ ninja -C out/Debug -j 10 root
The "root" parameter specifies the target to build, it's not a special keyword. You can find the "root" target in src/BUILD.gn.
(If you are a Googler, see the section at the end of this document for faster builds.)
You can also use the mojob.py script for building. This script automatically calls ninja and sets -j to an appropriate value based on whether Goma is present. You cannot specify a target name with this script.
mojo/tools/mojob.py build
Run a demo:
mojo/tools/mojo_demo.sh --browser
Run the tests:
mojo/tools/mojob.py test
You can update your repo like this:
$ gclient sync
$ git pull --rebase
You do not need to rerun "gn gen out/Debug". Ninja will do so automatically as needed.
With git you should make all your changes in a local branch. Once your change is committed, you can delete this branch.
Create a local branch named "mywork" and make changes to it.
cd src
git new-branch mywork
vi ...
Commit your change locally (this doesn't commit your change to the SVN or Git server)
git commit -a
If you added new files, you should tell git so by running git add <files> before committing.
Upload your change for review
git cl upload
Respond to review comments See Contributing code for more detailed git instructions, including how to update your CL when you get review comments. There's a short tutorial that might be helpful to try before your first change: C++ in Chromium 101.
To land a change after receiving LGTM:
$ git cl land
Don't break the build! Waterfall is here: http://build.chromium.org/p/client.mojo/waterfall
If you're a Googler, you can use Goma, a distributed compiler service for open-source projects such as Chrome and Android. The instructions below assume that Goma is installed in the default location (~/goma).
To enable Goma, update your "args.gn" file. Open the file in your editor with this command:
$ gn args out/Debug
Add this line to the end of the file:
use_goma = true
After you close the editor, the "gn args" command will automatically run "gn gen out/Debug" again.
Now you can dramatically increase the number of parallel tasks:
$ ninja -C out/Debug -j 1000 root