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Chromium rebases

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Emerick Rogul edited this page Mar 4, 2023 · 94 revisions

Configure and init the new Chromium version

  1. Create a new cloned directory and install the necessary node modules.

 npm install

  1. Since this is a new clone, you won't have a src directory so run init to create that.

 npm run init

  1. Branch off the latest Chromium rebase branch or master, whichever is applicable.

  2. Open package.json in src/brave/ and change the string at the path config.projects.chrome.tag to the new Chromium version, then commit the changes to that file with the comment Update from Chromium XXX to Chromium YYY.

  3. Run npm run sync to make sure that the Chromium repository at src/ is at the right version, the right internal dependencies are set to the expected versions, and the patches from Brave applied as expected.

  4. If all patches apply correctly, simply run

 npm run update_patches

 then, commit the changes with the comment Updated patches from Chromium XXX to Chromium YYY.

 Typically, however, some patches will fail to apply.

Fix patches

  1. Resolve errors for each patch that didn't apply.

 The most common situations are:

  • The file being patched got moved/renamed -> rename the patch accordingly.
  • The content of the file changed so that the lines surrounding the patched in lines don't match -> adjust the patch to fit the new content. Once the patch is fixed, apply it, then, update:
 cd src
 git apply -3 brave/patches/patch_name.patch
 git diff <CHROMIUM_VERSION> --src-prefix=a/ --dst-prefix=b/ --full-index path/to/file/being/patched > brave/patches/patch_name.patch

 When all such failing patches have been fixed, commit the changed patches with the comment Conflict-resolved patches from Chromium XXX to Chromium YYY.

  • The content that was being patched or the entire file was removed -> determine if the patch can just be removed or other changes need to made to compensate for the removed code. Remove the patch and commit. The commit message should include the links to the relevant upstream changes on https://chromium.googlesource.com/ or https://source.chromium.org/, as well as the upstream commit messages for those changes.
  1. Once all patching errors have been resolved, run update:

 npm run update_patches

 This will update patches that applied correctly in the first place. Commit the changes with the comment Updated patches from Chromium XXX to Chromium YYY.

  1. Since the init was interrupted by patching errors run sync:

 npm run sync

Note: Be careful when applying tools/gritsettings/resource_ids, sometimes the IDs can change and you should update the Brave one to be the same as the Chromium one.

Update strings

Update grd and grdp files from the Chromium ones:

cd ..
npm run chromium_rebase_l10n

Note: Filled some custom strings to brave_strings.grd by https://github.com/brave/brave-core/pull/214/commits/256f5aa8e781d266ad23f863ac7b613615ad2a5a

Inspect changed strings visually to catch overly aggressive replacements (e.g. Google Lens -> Brave Lens). If overly aggressive replacements are found, add them to script/lib/l10n/grd_string_replacements.py and script/lib/l10n/transifex/push.py and rerun the chromium_rebase_l10n script.

Do a commit for the updated source strings, grd files with the comment Updated strings for Chromium XXX.

Check for changes in the build tool chain

  • For Mac, check mac_sdk_min in src/build/config/mac/mac_sdk_overrides.gni for the SDK version, the comment above MAC_BINARIES_TAG and MAC_MINIMUM_OS_VERSION in src/build/mac_toolchain.py for the XCode version and the OS version,
  • For Windows check MSVS_VERSIONS in src/build/vs_toolchain.py (CURRENT_DEFAULT_TOOLCHAIN_VERSION in src/build/win_toolchain.py prior to C75) for Visual Studio versions.

Update your tool chain if needed and alert dev and CI teams on tool chain changes.

Fix the build

Do a build like normal, fix errors as they come up.

npm run build

If there's anything that should be called out as a non-trivial change, you should do it as a separate commit.

For each error fixed, the commit message should include the links to the relevant upstream changes on https://chromium.googlesource.com/ or https://source.chromium.org/, as well as the upstream commit messages for those changes.

If you have more fixes caused by the same upstream change, use git commit --fixup and rebase -i to squash them.

git log
1234567 Fix for upstream change A.
8910112 Fix for upstream change B.

git commit -a --fixup 1234567 
git rebase -i --autosquash @~3

Fix chromium_src overrides

Run brave/script/check_chromium_src.py to locate any override files in chromium_src override directory:

  • whose targets under src no longer exist
  • that contain definitions for symbols that are no longer present in the target file

Make an appropriate fix for each situation.

Fix unit and browser tests build

Build unit and browser tests as usual:

npm run test -- brave_unit_tests

npm run test -- brave_browser_tests

Use the same commit practices as for fixing the main build.

MIDL issue on Windows

When this message is visible during the build, check src/third_party/win_build_output/ is changed. If not, it means our pre-generated files in ./src/brave/win_build_output/midl/google_update/ are not copied there. In this case, check updateOmahaMidlFiles() in lib/util.js. Make sure that google_update directory has two directory(x64, x86).

To rebaseline:
  copy /y c:\users\XXX\appdata\local\temp\tmpdjhho_\* C:\Projects\brave\brave-browser\src\third_party\win_build_output\midl\google_update\x64

Audit for new network services

When submitting PR on Github add CI/run-network-audit label to the PR to ensure that the CI runs audit-network.

For now just follow the instructions in https://github.com/brave/brave-browser/wiki/Tests#privacy-network-audit.

We should build some automation to find new things added here:

https://cs.chromium.org/search/?q=%22destination:+GOOGLE_OWNED_SERVICE%22&sq=package:chromium&type=cs

Check for changes in supported OS versions

  • For MacOS check mac_deployment_target and mac_min_system_version in build/config/mac/mac_sdk.gni
  • For iOS check ios_deployment_target in build/config/ios/ios_sdk_overrides.gni

Notify Security team of feature changes

  • Check with the Security team in regards to any possibly relevant changes in features or their default settings. Specifically, post link to changes in https://chromium.googlesource.com/chromium/src/+diff/[PreviousVersion]..[NewVersion]/content/public/common/content_features.cc in #security-discussion Slack channel.

  • Besides new settings, we'll want to look at brave://components and see if there are new components registered. For example, there are components we have either missed (when added) or we never triaged captured in this GitHub issue. There's an issue created to automate this process which you can find here.

  • Entitlements to enable new features specific to Chrome are added to https://source.chromium.org/chromium/chromium/src/+/master:chrome/app/app-entitlements-chrome.plist.Review the new entitlements for each CR bump when new features are added to Chrome.

  • On Android, new permissions can be added in */AndroidManifest.xml or */AndroidManifest.xml.expected. Users often ask questions about new permissions on update. Any new permissions should be reviewed by the @android-team or @security-team before merge.

Update localizations

See https://github.com/brave/brave-browser/wiki/Strings-and-Localization

Run this to detect new strings and push them to Transifex, it will also push up the translations for those strings automatically. If you need access talk to devops.

npm run push_l10n

Run this to pull down new xtb and translation files:

npm run pull_l10n

Do a commit for all the string translation updates, xtb files.

Creating the PR

When creating the PR, mark it as WIP and put it into draft mode. The title should be Upgrade from Chromium {n} to Chromium {n+1} where n is the current version number.

The PR must contain all of the following labels:

  • CI/run-audit-deps
  • CI/run-draft
  • CI/run-network-audit
  • CI/run-upstream-tests

Smoke test

Before handing off a build to QA, please test the following functionality:

  • Ensure that About page shows the expected version number
  • Ensure that brave://settings is functional and not throwing any console errors
  • Ensure that clearing browser data on exit works as expected
  • Ensure that tabs have the expected shape (it's slightly different from Chrome)
  • Ensure that videos play properly on YouTube and that the media device toolbar button works correctly
  • Ensure that tab-muting works properly
  • Ensure that vertical tabs work as expected (must first enable this via brave://flags)
  • Ensure that enabling Rewards works properly
  • Ensure that all elements of the sidebar panel work as expected
  • Enusre that creating and using multiple profiles works as expected
  • Ensure that private and Tor windows work as expected
  • Ensure that a few different web sites load as expected

Before merging

Make builds for QA smoke tests using the following links:

Settings:

  • CHANNEL - Set to nightly (this is the default)
  • BRANCH - Set to the appropriate branch name, e.g., cr100
  • PREVIOUS_BUILD_NUMBER_DELTA - Leave blank
  • KEYCHAIN_NAME (Mac only) - Must be set to release (this is now the default, but always double-check it as using the wrong setting will result in an app that crashes on startup)

Those build jobs produce installers that you can retrieve from the following places (you'll need to modify these links slightly, as they include build and version number information; they're provided here only as an example):

MacOS installers

Linux installers

Windows (x64) installers

Windows (x86) installers

Android installers

iOS installers

Merge

After QA signoff on the test builds, merge to master and announce it on the appropriate Slack channels. At this time, you can also note for developers any process/style/etc. changes required by the new Chromium version.

After merging to master create uplifts as appropriate.

Minor bumps

For post-merge minor Chromium bumps, follow the instructions here.

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