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Checking out and building Chromium for iOS

There are instructions for other platforms linked from the get the code page.

Instructions for Google Employees

Are you a Google employee? See go/building-chrome instead.

[TOC]

System requirements

  • A 64-bit Mac capable of running the required version of Xcode.
  • Xcode 15.0 or higher.

Note: after installing Xcode, you need to launch it and to let it install the iOS simulator. This is required as part of the build, see this discussion on chromium-dev.

Install depot_tools

Clone the depot_tools repository:

$ git clone https://chromium.googlesource.com/chromium/tools/depot_tools.git

Add depot_tools to the end of your PATH (you will probably want to put this in your ~/.bashrc or ~/.zshrc). Assuming you cloned depot_tools to /path/to/depot_tools:

$ export PATH="$PATH:/path/to/depot_tools"

Get the code

Create a chromium directory for the checkout and change to it (you can call this whatever you like and put it wherever you like, as long as the full path has no spaces):

$ mkdir chromium && cd chromium

Run the fetch tool from depot_tools to check out the code and its dependencies.

$ fetch ios

If you don't want the full repo history, you can save a lot of time by adding the --no-history flag to fetch.

Expect the command to take 30 minutes on even a fast connection, and many hours on slower ones.

When fetch completes, it will have created a hidden .gclient file and a directory called src in the working directory. The remaining instructions assume you have switched to the src directory:

$ cd src

Optional: You can also install API keys if you want your build to talk to some Google services, but this is not necessary for most development and testing purposes.

Setting up the build

Since the iOS build is a bit more complicated than a desktop build, we provide ios/build/tools/setup-gn.py, which will create four appropriately configured build directories under out for Release and Debug device and simulator builds, and generates an appropriate Xcode project (out/build/all.xcodeproj) as well.

More information about developing with Xcode. Xcode project is an artifact, any changes made in the project itself will be ignored.

You can customize the build by editing the file $HOME/.setup-gn (create it if it does not exist). Look at src/ios/build/tools/setup-gn.config for available configuration options.

From this point, you can either build from Xcode or from the command line using autoninja. setup-gn.py creates sub-directories named out/${configuration}-${platform}, so for a Debug build for simulator use:

$ autoninja -C out/Debug-iphonesimulator gn_all

(autoninja is a wrapper that automatically provides optimal values for the arguments passed to ninja.)

Note: The setup-gn.py script needs to run every time one of the BUILD.gn files is updated (either by you or after rebasing). If you forget to run it, the list of targets and files in the Xcode solution may be stale. You can run the script directly or use either gclient sync or gclient runhooks which will run setup-gn.py for you as part of the update hooks.

You can add a custom hook to .gclient file to configure setup-gn.py to be run as part of gclient runhooks. In that case, your .gclient file would look like this:

solutions = [
  {
    "name"        : "src",
    "url"         : "https://chromium.googlesource.com/chromium/src.git",
    "deps_file"   : "DEPS",
    "managed"     : False,
    "custom_deps" : {},
    "custom_vars" : {},
    "custom_hooks": [{
      "name": "setup_gn",
      "pattern": ".",
      "action": [
        "python3",
        "src/ios/build/tools/setup-gn.py",
      ]
    }],
    "safesync_url": "",
  },
]
target_os = ["ios"]
target_os_only = True

You can also follow the manual instructions on the Mac page, but make sure you set the GN arg target_os="ios".

Faster builds

This section contains some things you can change to speed up your builds, sorted so that the things that make the biggest difference are first.

Use Reclient

Google employees should use Reclient, a distributed compilation system. Detailed information is available internally but the relevant gn arg is:

  • use_remoteexec = true

Google employees can visit go/building-chrome-mac#using-remote-execution for more information. For external contributors, Reclient does not support iOS builds.

Building for device

To be able to build and run Chromium and the tests for devices, you need to have an Apple developer account (a free one will work) and the appropriate provisioning profiles, then configure the build to use them.

Code signing identity

Please refer to the Apple documentation on how to get a code signing identity and certificates. You can check that you have a code signing identity correctly installed by running the following command.

$ xcrun security find-identity -v -p codesigning
  1) 0123456789ABCDEF0123456789ABCDEF01234567 "iPhone Developer: someone@example.com (XXXXXXXXXX)"
     1 valid identities found

If the command output says you have zero valid identities, then you do not have a code signing identity installed and need to get one from Apple. If you have more than one identity, the build system may select the wrong one automatically, and you can use the ios_code_signing_identity gn variable to control which one to use by setting it to the identity hash, e.g. to "0123456789ABCDEF0123456789ABCDEF01234567".

Mobile provisioning profiles

Once you have the code signing identity, you need to decide on a prefix for the application bundle identifier. This is controlled by the gn variable ios_app_bundle_id_prefix and usually corresponds to a reversed domain name (the default value is "org.chromium").

You then need to request provisioning profiles from Apple for your devices for the following bundle identifiers to build and run Chromium with these application extensions:

  • ${prefix}.chrome.ios.dev
  • ${prefix}.chrome.ios.dev.ContentTodayExtension
  • ${prefix}.chrome.ios.dev.CredentialProviderExtension
  • ${prefix}.chrome.ios.dev.IntentsExtension
  • ${prefix}.chrome.ios.dev.OpenExtension
  • ${prefix}.chrome.ios.dev.ShareExtension
  • ${prefix}.chrome.ios.dev.TodayExtension
  • ${prefix}.chrome.ios.dev.WidgetKitExtension

All these certificates need to have the "App Groups" (com.apple.security.application-groups) capability enabled for the following groups:

  • group.${prefix}.chrome
  • group.${prefix}.common

The group.${prefix}.chrome is only shared by Chromium and its extensions to share files and configurations while the group.${prefix}.common is shared with Chromium and other applications from the same organisation and can be used to send commands to Chromium.

${prefix}.chrome.ios.dev and ${prefix}.chrome.ios.dev.CredentialProviderExtension need the AutoFill Credential Provider Entitlement, which corresponds to the key com.apple.developer.authentication-services.autofill-credential-provider.

${prefix}.chrome.ios.dev additionally needs the com.apple.developer.kernel.extended-virtual-addressing entitlement when running on a real device.

Mobile provisioning profiles for tests

In addition to that, you need a different provisioning profile for each test application. Those provisioning profile will have a bundle identifier matching the following pattern ${prefix}.gtest.${test-suite-name} where ${test-suite-name} is the name of the test suite with underscores changed to dashes (e.g. base_unittests app will use ${prefix}.gtest.base-unittests as bundle identifier).

To be able to run the EarlGrey tests on a device, you'll need two provisioning profiles for EarlGrey and OCHamcrest frameworks:

  • ${prefix}.test.OCHamcrest
  • ${prefix}.test.EarlGrey

In addition to that, then you'll need one additional provisioning profile for the XCTest module too. It must match the pattern: ${prefix}.gtest.${test-suite-name}-module.

Other applications

Other applications like ios_web_shell usually will require mobile provisioning profiles with bundle identifiers that may usually match the following pattern ${prefix}.${application-name} and may require specific capabilities.

Generally, if the mobile provisioning profile is missing then the code signing step will fail and will print the bundle identifier of the bundle that could not be signed on the command line, e.g.:

$ autoninja -C out/Debug-iphoneos ios_web_shell
ninja: Entering directory `out/Debug-iphoneos'
FAILED: ios_web_shell.app/ios_web_shell ios_web_shell.app/_CodeSignature/CodeResources ios_web_shell.app/embedded.mobileprovision
python ../../build/config/ios/codesign.py code-sign-bundle -t=iphoneos -i=0123456789ABCDEF0123456789ABCDEF01234567 -e=../../build/config/ios/entitlements.plist -b=obj/ios/web/shell/ios_web_shell ios_web_shell.app
Error: no mobile provisioning profile found for "org.chromium.ios-web-shell".
ninja: build stopped: subcommand failed.

Here, the build is failing because there are no mobile provisioning profiles installed that could sign the ios_web_shell.app bundle with the identity 0123456789ABCDEF0123456789ABCDEF01234567. To fix the build, you'll need to request such a mobile provisioning profile from Apple.

You can inspect the file passed via the -e flag to the codesign.py script to check which capabilities are required for the mobile provisioning profile (e.g. src/build/config/ios/entitlements.plist for the above build error, remember that the paths are relative to the build directory, not to the source directory).

If the required capabilities are not enabled on the mobile provisioning profile, then it will be impossible to install the application on a device (Xcode will display an error stating that "The application was signed with invalid entitlements").

Building Blink for iOS

The iOS build supports compiling the blink web platform. To compile blink set a gn arg in your .setup-gn file. Note the blink web platform is experimental code and should only be used for analysis.

[gn_args]
use_blink = true

Note that only certain targets support blink. content_shell being the most useful.

$ autoninja -C out/Debug-iphonesimulator content_shell

Running apps from the command line

Any target that is built and runs on the bots (see below) should run successfully in a local build. To run in the simulator from the command line, you can use iossim. For example, to run a debug build of Chromium:

$ out/Debug-iphonesimulator/iossim -i out/Debug-iphonesimulator/Chromium.app

From Xcode 9 on, iossim no longer automatically launches the Simulator. This must now be done manually from within Xcode (Xcode > Open Developer Tool > Simulator), and also must be done after running iossim.

Passing arguments

Arguments needed to be passed to the test application through iossim, such as --gtest_filter=SomeTest.FooBar should be passed through the -c flag:

$ out/Debug-iphonesimulator/iossim -i \
    -c "--gtest_filter=SomeTest.FooBar --gtest_repeat=3" \
    out/Debug-iphonesimulator/base_unittests.app

Running EarlGrey tests

EarlGrey tests are run differently than other test targets, as there is an XCTest bundle that is injected into the target application. Therefore you must also pass in the test bundle:

$ out/Debug-iphonesimulator/iossim -i \
    out/Debug-iphonesimulator/ios_chrome_ui_egtests.app \
    out/Debug-iphonesimulator/ios_chrome_ui_egtests.app/PlugIns/ios_chrome_ui_egtests_module.xctest

Running Web Tests on Blink for iOS

The current Blink for iOS only supports running Web Tests on the simulator environment now. Before you run the web tests, you need to build the blink_tests target to get content_shell and all of the other needed binaries for the simulator test environment.

$ autoninja -C out/Debug-iphonesimulator blink_tests

When the blink_tests target is complete you can then run the test runner script (third_party/blink/tools/run_web_tests.py) as below. See Web Tests document for more information.

$ third_party/blink/tools/run_web_tests.py -t Debug-iphonesimulator \
    --platform ios

Running on specific simulator

By default, iossim will pick an arbitrary simulator to run the tests. If you want to run them on a specific simulator, you can use -d to pick the simulated device and -s to select the iOS version.

For example, to run the tests on a simulated iPhone 6s running iOS 10.0, you would invoke iossim like this.

$ out/Debug-iphonesimulator/iossim -i -d 'iPhone 6s' -s '10.0' \
    out/Debug-iphonesimulator/base_unittests.app

Please note that by default only a subset of simulator devices are installed with Xcode. You may have to install additional simulators in Xcode (or even an older version of Xcode) to be able to run on a specific configuration.

Go to "Preferences > Components" tab in Xcode to install other simulator images (this is the location the setting is in Xcode 9.2; it may be different in other version of the tool).

Remote debugging with DevTools (on Blink for iOS)

Developers are able to remotely use DevTools in a host machine (e.g. Mac) and inspect content_shell for development.

On the simulator, one just needs to pass the --remote-debugging-port=9222 argument for content_shell and in the host machine access it via chrome://inspect. It is possible to change the default port listening (9222) and configure another one via the "Configure…" button and then "Target discovery settings" dialog.

To use DevTools in the remote device it is necessary to also pass the remote debugging address argument to content-shell so any address could bind for debugging: --remote-debugging-address=0.0.0.0 --remote-debugging-port=9222. Then in the host machine one needs to configure the IP address of the device in the "Target discovery settings" dialog e.g. 192.168.0.102:9222.

Update your checkout

To update an existing checkout, you can run

$ git rebase-update
$ gclient sync

The first command updates the primary Chromium source repository and rebases any of your local branches on top of tip-of-tree (aka the Git branch origin/main). If you don't want to use this script, you can also just use git pull or other common Git commands to update the repo.

The second command syncs dependencies to the appropriate versions and re-runs hooks as needed.

Tips, tricks, and troubleshooting

Remember that the XCode project you interact with while working on Chromium is a build artifact, generated from the BUILD.gn files. Do not use it to add new files; instead see the procedures for working with files.

If you have problems building, join us in #chromium on irc.freenode.net and ask there. As mentioned above, be sure that the waterfall is green and the tree is open before checking out. This will increase your chances of success.

Debugging

To help with deterministic builds, and to work with reclient, the path to source files in debugging symbols are relative to source directory. To allow Xcode to find the source files, you need to ensure to have an ~/.lldbinit-Xcode file with the following lines into it (substitute {SRC} for your actual path to the root of Chromium's sources):

script sys.path[:0] = ['{SRC}/tools/lldb']
script import lldbinit

This will also allow you to see the content of some of Chromium types in the debugger like std::u16string, ... If you want to use lldb directly, name the file ~/.lldbinit instead of ~/.lldbinit-Xcode.

Note: if you are using ios/build/tools/setup-gn.py to generate the Xcode project, the script also generate an .lldbinit file next to the project and configure Xcode to use that file instead of the global one.

Changing the version of Xcode

To change the version of Xcode used to build Chromium on iOS, please follow the steps below:

  1. Launch the new version of Xcode.app.

    This is required as Xcode may need to install some components into the system before the new version can be used from the command-line.

  2. Reboot your computer.

    This is required as some of Xcode components are daemons that are not automatically stopped when updating Xcode, and command-line tools will fail if the daemon version is incompatible (usually actool fails).

  3. Run gn gen.

    This is required as the ninja files generated by gn encodes some information about Xcode (notably the path to the SDK, ...) that will change with each version. It is not possible to have ninja re-run gn gen automatically when those changes unfortunately.

    If you have a downstream chekout, run gclient runhooks instead of gn gen as it will ensure that gn gen will be run automatically for all possible combination of target and configuration from within Xcode.

If you skip some of those steps, the build may occasionally succeed, but it has been observed in the past that those steps are required in the vast majority of the situation. Please save yourself some painful build debugging and follow them.

If you use xcode-select to switch between multiple version of Xcode, you will have to follow the same steps.

Improving performance of git commands

Increase the vnode cache size

git status is used frequently to determine the status of your checkout. Due to the large number of files in Chromium's checkout, git status performance can be quite variable. Increasing the system's vnode cache appears to help. By default, this command:

$ sysctl -a | egrep kern\..*vnodes

Outputs kern.maxvnodes: 263168 (263168 is 257 * 1024). To increase this setting:

$ sudo sysctl kern.maxvnodes=$((512*1024))

Higher values may be appropriate if you routinely move between different Chromium checkouts. This setting will reset on reboot, the startup setting can be set in /etc/sysctl.conf:

$ echo kern.maxvnodes=$((512*1024)) | sudo tee -a /etc/sysctl.conf

Or edit the file directly.

Configure git to use an untracked cache

Try running

$ git update-index --test-untracked-cache

If the output ends with OK, then the following may also improve performance of git status:

$ git config core.untrackedCache true

Configure git to use fsmonitor

You can significantly speed up git by using fsmonitor. You should enable fsmonitor in large repos, such as Chromium and v8. Enabling it globally will launch many processes and probably isn't worthwhile. Be sure you have at least version 2.43 (fsmonitor on the Mac is broken before then). The command to enable fsmonitor in the current repo is:

$ git config core.fsmonitor true

Xcode license agreement

If you're getting the error

Agreeing to the Xcode/iOS license requires admin privileges, please re-run as root via sudo.

the Xcode license hasn't been accepted yet which (contrary to the message) any user can do by running:

$ xcodebuild -license

Only accepting for all users of the machine requires root:

$ sudo xcodebuild -license