commit: a404e9047cdeb9dc38a0b0bafd45ee1f489e391c
[log]
author: kenoss <kenoss@chromium.org>
Mon Sep 07 23:46:56 2026
committer: LUCI CQ <infra-scoped@luci-project-accounts.iam.gserviceaccount.com>
Mon Sep 07 23:46:56 2026
tree: 19b6e23b4cdd53d242bf9b0c561902fb780182a3
parent: 69a652ea05e450f84620f56957a801923186fda5 [diff]

Reland "gclient: Add Chrome Trace Event format support for Perfetto UI"

This is a reland of commit c56fec68473515b44f1ddaea7a23fb66d88e4048

Diff from the original: In Python < 3.9, `collections.abc.Iterator` is
not subscriptable and raises `TypeError: 'ABCMeta' object is not
subscriptable` when evaluated as `Iterator[None]` at import time (e.g.
when imported via gsutil.py). Import `Iterator` from `typing` instead to
ensure compatibility with older Python environments.

Original change's description:
> gclient: Add Chrome Trace Event format support for Perfetto UI
>
> Add lightweight, zero-dependency tracing support to gclient to record
> timelines of parallel git syncs, CIPD downloads, and individual hooks.
> Traces can be viewed directly in https://ui.perfetto.dev.
>
> This is for investigating why gclient is slow.
>
> Examples:
>
> - https://drive.google.com/file/d/1BQfoNwi8hpOwMxgTnGG3LpVMqkidu63w/view?usp=drive_link
> - https://drive.google.com/file/d/1xHc1ZGo-QiyPi9UDEQRiT2yMT4TbSBV6/view?usp=drive_link
>
> See also https://crrev.com/c/8256812.
>
> Bug: none
> Change-Id: I5ebbcc86d6d940b1198d62afe911665c794b9b52
> Co-Authored-By: Gemini <noreply@google.com>
> TAG=agy
> CONV=a8dcce58-7d95-4a6e-822b-4816067f284f
> Reviewed-on: https://chromium-review.googlesource.com/c/chromium/tools/depot_tools/+/8260569
> Reviewed-by: Gavin Mak <gavinmak@google.com>
> Commit-Queue: Gavin Mak <gavinmak@google.com>
> Auto-Submit: Ken Okada <kenoss@chromium.org>

Bug: none
Change-Id: I92dadf3a502b5aeecc01f80ff17259d4da14eb29
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/tools/depot_tools/+/8356909
Commit-Queue: Ken Okada <kenoss@chromium.org>
Reviewed-by: Alex Ovsienko <ovsienko@google.com>

5 files changed

tree: 19b6e23b4cdd53d242bf9b0c561902fb780182a3

README.md

depot_tools

Tools for Chromium development. Requires Python 3.8+.

gsutil: Python 3.9–3.13 required.

Tools

The most important tools are:

fetch: A gclient wrapper to checkout a project. Use fetch --help for more details.
gclient: A meta-checkout tool. Think repo or git submodules, except that it support OS-specific rules, e.g. do not checkout Windows only dependencies when checking out for Android. Use gclient help for more details and README.gclient.md.
git cl: A code review tool to interact with Rietveld or Gerrit. Use git cl help for more details and README.git-cl.md.
roll-dep: A gclient dependency management tool to submit a dep roll, updating a dependency to a newer revision.

There are a lot of git utilities included.

Also, includes shell script/batch file for tools required to build chromium, e.g.

gn: a meta-build system that generates build files for Ninja
autoninja: a wrapper for siso and ninja.
siso: a build tool that aims to significantly speed up Chromium's build.
ninja: a small build system with a focus on speed. deprecated by Siso.

These shell script/batch file runs python script with python-bin/python3 that find binaries in chromium checkout, and run with proper setup/check. To use these wrappers, you need to initialize/bootstrap depot_tools (using gclient, update_depot_tools or ensure_bootstrap).

AI agent tooling

This repository contains two separate directories of agent-related tooling with distinct audiences:

agents/: Skills and configuration meant for Chromium developers (and their AI agents) working in the Chromium codebase using depot_tools.
depot_tools_agents/: AI review agents (e.g. Gerrit review agents) meant only for maintainers of depot_tools working on the depot_tools code itself. This is not intended for use with the Chromium codebase.

Installing

See set-up documentation.

depot_tools is also available in

chromium's third_party/depot_tools: propagated by autoroller.
on builder: infra_internal/recipe_bundles/chrome-internal.googlesource.com/chrome/tools/build bundles depot_tools. propagated by build_internal recipe roller

These depot_tools would not be initialized/bootstrapped (i.e. no python-bin/python3 binary available), so the build tool wrapper won't work, unless it is explicitly initialized by ensure_bootstrap. Or, directly call the python script instead of using the shell script/batch file.

Updating

depot_tools updates itself automatically when running gclient tool. To disable auto update, set the environment variable DEPOT_TOOLS_UPDATE=0 or run ./update_depot_tools_toggle.py --disable.

To update package manually, run update_depot_tools.bat on Windows, or ./update_depot_tools on Linux or Mac.

Running gclient will install python3 binary.

Contributing

To contribute change for review:

git new-branch <somename>
# Hack
git add .
git commit -a -m "Fixes goat teleporting"
# find reviewers
git cl owners
git log -- <yourfiles>

# Request a review.
git cl upload -r reviewer1@chromium.org,reviewer2@chromium.org --send-mail

# Edit change description if needed.
git cl desc

# If change is approved, flag it to be committed.
git cl set-commit

# If change needs more work.
git rebase-update
...
git cl upload -t "Fixes goat teleporter destination to be Australia"

See also open bugs, open reviews, forum or report problems.

cpplint.py

Until 2018, our cpplint.py was a copy of the upstream version at https://github.com/google/styleguide/tree/gh-pages/cpplint. Unfortunately, that repository is not maintained any more. If you want to update cpplint.py in depot_tools, just upload a patch to do so. We will figure out a long-term strategy via issue https://crbug.com/916550.