Chrome DevTools frontend
The client-side of the Chrome DevTools, including all JS & CSS to run the DevTools webapp.
Source code
The frontend is available on chromium.googlesource.com.
Design Guidelines
Please be aware that DevTools follows additional development guidelines.
Issue triage
The issue triage guidelines can be found here.
Workflows
In order to make changes to DevTools frontend, build, run, test, and submit changes, several workflows exist. Having depot_tools set up is a common prerequisite.
Integrate standalone checkout into Chromium (strongly recommended)
This workflow will ensure that your local setup is equivalent to how Chromium infrastructure tests your change. It also allows you to develop DevTools independently of the version in your Chromium checkout. This means that you don't need to update Chromium often, in order to work on DevTools.
Remove Existing devtools-frontend subrepository
In chromium/src
, run gclient sync
to make sure you have installed all required submodules.
gclient sync
Then, disable gclient sync
for DevTools frontend inside of Chromium by editing .gclient
config. From chromium/src/
, simply run
vim $(gclient root)/.gclient
In the custom_deps
section, insert this line:
"src/third_party/devtools-frontend/src": None,
Then run
gclient sync -D
This removes the DevTools frontend dependency. We now create a symlink to refer to the standalone checkout (execute in chromium/src
and make sure that third_party/devtools-frontend
exists):
(Note that the folder names do NOT include the trailing slash)
Workflow 1: separate gclient projects
Now, There are 2 approaches to integrating your workflows: The first approach is to have separate gclient projects, one for each repository, and manually symlink between the two
Running gclient sync
in chromium/src/
will update dependencies for the Chromium checkout.
Running gclient sync
in chromium/src/third_party/devtools-frontend/src
will update dependencies for the standalone checkout.
Workflow 2: a single gclient project
The second approach is to have a single gclient project that automatically gclient sync's all dependencies for both repositories
solutions = [
{
# Chromium src project
"url": "https://chromium.googlesource.com/chromium/src.git",
"managed": False,
"name": "src",
"custom_deps": {
"src/third_party/devtools-frontend/src": None,
},
"custom_vars": {},
},
{
# devtools-frontend project
"name": "devtools-frontend",
"url": "https://chromium.googlesource.com/devtools/devtools-frontend",
"custom_deps": {}
}
]
Run gclient sync
once in chromium/src/
to get the new devtools frontend checkout.
Running gclient sync
anywhere within chromium/src/
or chromium/src/third_party/devtools-frontend/src
will update dependencies for both checkouts.
Automatic Symlink
To automatically symlink between the devtools-frontend and chromium/src, you can add the following hook to your .gclient file that manages your chromium/src repository after your list of solutions
hooks = [
{
# Ensure devtools is symlinked in the correct location on every gclient sync
'name': 'Symlink Depot Tools',
'pattern': '.',
'action': [
'python',
'<path>/<to>/devtools-frontend/scripts/deps/ensure_symlink.py',
'<path>/<to>/chromium/src',
'<path>/<to>/devtools-frontend'
],
}
]
Now, running gclient sync -D
will no longer remove your symlink.
Standalone workflow
As a standalone project, Chrome DevTools frontend can be checked out and built independently from Chromium. The main advantage is not having to check out and build Chromium. However, there is also no way to run layout tests in this workflow.
Checking out source
To check out the source for DevTools frontend only, follow these steps:
mkdir devtools
cd devtools
fetch devtools-frontend
Build
To build, follow these steps:
cd devtools-frontend
gn gen out/Default
autoninja -C out/Default
The resulting build artifacts can be found in out/Default/resources/inspector
.
Update to latest
To update to latest tip of tree version:
git fetch origin
git checkout origin/master
gclient sync
Run in Chromium
These steps work with Chromium 79 or later. To run the production build, use
(Requires brew install coreutils
on Mac.)
<path-to-chrome>/chrome --custom-devtools-frontend=file://$(realpath out/Default/resources/inspector)
You can inspect DevTools with DevTools by undocking DevTools and then open the developers tools (F12 on Windows/Linux, Cmd+Option+I on Mac).
Test
Test are available by running scripts in scripts/test/
.
Create a change
Usual steps for creating a change work out of the box.
Managing dependencies
Note that this will only work with the above two workflows
- To sync dependencies from Chromium to DevTools frontend, use
scripts/deps/roll_deps.py && npm run generate-protocol-resources
.
The following scripts run as AutoRollers, but can be manually invoked if desired:
- To roll the HEAD commit of DevTools frontend into Chromium, use
scripts/deps/roll_to_chromium.py
. - To update DevTools frontend's DEPS, use
roll-dep
.
Chromium workflow (discouraged)
DevTools frontend can also be developed as part of the full Chromium checkout. This workflow can be used to make small patches to DevTools as a Chromium engineer. However, it is different to our infrastructure setup and how to execute general maintenance work.
Checking out source
Follow instructions to check out Chromium. DevTools frontend can be found under third_party/devtools-frontend/src/
.
Build
Refer to instructions to build Chromium. To only build DevTools frontend, use devtools_frontend_resources
as build target. The resulting build artifacts for DevTools frontend can be found in out/Default/resources/inspector
.
Run
Run Chrome with DevTools frontend bundled:
out/Default/chrome
Test
Test are available by running scripts in third_party/devtools-frontend/src/scripts/test/
.
After building content shell, we can also run layout tests that are relevant for DevTools frontend:
autoninja -C out/Default content_shell
third_party/blink/tools/run_web_tests.py http/tests/devtools
Create a change
Usual steps for creating a change work out of the box, when executed in third_party/devtools-frontend/src/
.
Testing
Please refer to the overview document. The current test status can be seen at the test waterfall.
Additional references
- DevTools documentation: devtools.chrome.com
- Debugging protocol docs and Chrome Debugging Protocol Viewer
- awesome-chrome-devtools: recommended tools and resources
- Contributing to DevTools: bit.ly/devtools-contribution-guide
- Contributing To Chrome DevTools Protocol: docs.google.com
- DevTools Design Review Guidelines: DESGN_GUIDELINES.MD
Merges and Cherry-Picks
Merge request/approval is handled by Chromium Release Managers. DevTools follows The Zen of Merge Requests. In exceptional cases please get in touch with hablich@chromium.org.
Step-by-step guide on how to merge:
- Request and receive approval to merge
- Backmerges are done to the chromium/xxxx (e.g. chromium/3979) branch respectively on the DevTools frontend repo
- Use Omahaproxy to find out what branch a major Chromium version has (column true_branch). Open the to-be-merged commit in Gerrit e.g. Example
- Click hamburger menu on the top right and select Cherry Pick
- Select branch to merge to e.g. chromium/3968
- Cherry Pick CL is created e.g. Example
- Get it reviewed if necessary
- Click hamburger menu on the cherry pick CL and select Submit
- Done
Useful Commands
git cl format --js
Formats all code using clang-format.
npm run check
Runs all static analysis checks on DevTools code.
Source mirrors
DevTools frontend repository is mirrored on GitHub.
DevTools frontend is also available on NPM as the chrome-devtools-frontend package. It's not currently available via CJS or ES2015 modules, so consuming this package in other tools may require some effort.
The version number of the npm package (e.g. 1.0.373466
) refers to the Chromium commit position of latest frontend git commit. It's incremented with every Chromium commit, however the package is updated roughly daily.
Getting in touch
- All devtools commits: View the log or follow @DevToolsCommits on Twitter
- All open DevTools tickets on crbug.com
- File a new DevTools ticket: new.crbug.com
- Code reviews mailing list: devtools-reviews@chromium.org
- @ChromeDevTools on Twitter
- Chrome DevTools mailing list: groups.google.com/forum/google-chrome-developer-tools