docs/android_build_instructions.md - chromium/src.git - Git at Google

 # Checking out and building Chromium for Android

 There are instructions for other platforms linked from the
 [get the code](get_the_code.md) page.

 ## Instructions for Google Employees

 Are you a Google employee? See
 [go/building-android-chrome](https://goto.google.com/building-android-chrome)
 instead.

 [TOC]

 ## System requirements

 * An x86-64 machine running Linux with at least 8GB of RAM. More than 16GB is
   highly recommended.
 * At least 100GB of free disk space.
 * You must have Git and Python installed already.

 Most development is done on Ubuntu. Other distros may or may not work;
 see the [Linux instructions](linux/build_instructions.md) for some suggestions.

 Building the Android client on Windows or Mac is not supported and doesn't work.

 ## Install depot\_tools

 Clone the `depot_tools` repository:

 ```shell
 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`:

 ```shell
 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):

 ```shell
 mkdir ~/chromium && cd ~/chromium
 fetch --nohooks android
 ```

 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.

 If you've already installed the build dependencies on the machine (from another
 checkout, for example), you can omit the `--nohooks` flag and `fetch`
 will automatically execute `gclient runhooks` at the end.

 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:

 ```shell
 cd src
 ```

 ### Converting an existing Linux checkout

 If you have an existing Linux checkout, you can add Android support by
 appending `target_os = ['linux', 'android']` to your `.gclient` file (in the
 directory above `src`):

 ```shell
 echo "target_os = [ 'linux', 'android' ]" >> ../.gclient
 ```

 Then run `gclient sync` to pull the new Android dependencies:

 ```shell
 gclient sync
 ```

 (This is the only difference between `fetch android` and `fetch chromium`.)

 ### Install additional build dependencies

 Once you have checked out the code, run

 ```shell
 build/install-build-deps.sh
 ```

 to get all of the dependencies you need to build on Linux, *plus* all of the
 Android-specific dependencies (you need some of the regular Linux dependencies
 because an Android build includes a bunch of the Linux tools and utilities).

 NOTE: For 32-bit builds, the `--lib32` command line switch could be used.
 You may run into issues where `gperf` or `pkgconf` don't get installed,
 without it. To remedy this, and potentially other missing packages, you will
 have to install them manually using:

 ```shell
 sudo apt-get install {missing_pkg}
 ```

 ### Run the hooks

 Once you've run `install-build-deps` at least once, you can now run the
 Chromium-specific hooks, which will download additional binaries and other
 things you might need:

 ```shell
 gclient runhooks
 ```

 *Optional*: You can also [install API
 keys](https://www.chromium.org/developers/how-tos/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

 Chromium uses [Ninja](https://ninja-build.org) as its main build tool along with
 a tool called [GN](https://gn.googlesource.com/gn/+/main/docs/quick_start.md)
 to generate `.ninja` files. You can create any number of *build directories*
 with different configurations. To create a build directory which builds Chrome
 for Android, run `gn args out/Default` and edit the file to contain the
 following arguments:

 ```gn
 target_os = "android"
 target_cpu = "arm64"  # See "Figuring out target_cpu" below
 use_remoteexec = true  # Enables distributed builds. See "Faster Builds".
 android_static_analysis = "build_server"  # Does static checks in background. See "Faster Builds".
 ```

 * You only have to run this once for each new build directory, Ninja will
   update the build files as needed.
 * You can replace `Default` with another name, but
   it should be a subdirectory of `out`.
 * For other build arguments, including release settings, see [GN build
   configuration](https://www.chromium.org/developers/gn-build-configuration).
   The default will be a debug component build.
 * For more info on GN, run `gn help` on the command line or read the
   [quick start guide](https://gn.googlesource.com/gn/+/main/docs/quick_start.md).

 Also be aware that some scripts (e.g. `tombstones.py`, `adb_gdb.py`)
 require you to set `CHROMIUM_OUTPUT_DIR=out/Default`.

 ### Figuring out target\_cpu

 The value of
 [`target_cpu`](https://gn.googlesource.com/gn/+/main/docs/reference.md#var_target_cpu)
 determines what instruction set to use for native code. Given a device (or
 emulator), you can determine the correct instruction set with `adb shell getprop
 ro.product.cpu.abi`:

 | `getprop ro.product.cpu.abi` output | `target_cpu` value |
 |-------------------------------------|--------------------|
 | `arm64-v8a`                         | `arm64`            |
 | `armeabi-v7a`                       | `arm`              |
 | `x86`                               | `x86`              |
 | `x86_64`                            | `x64`              |

 *** promo
 `arm` and `x86` may optionally be used instead of `arm64` and `x64` for
 non-WebView targets. This is also allowed for Monochrome, but only when not set
 as the WebView provider.
 ***

 ## Build Chromium

 Build Chromium with Ninja using the command:

 ```shell
 autoninja -C out/Default chrome_public_apk
 ```

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

 You can get a list of all of the other build targets from GN by running `gn ls
 out/Default` from the command line. To compile one, pass the GN label to Ninja
 with no preceding "//" (so, for `//chrome/test:unit_tests` use `autoninja -C
 out/Default chrome/test:unit_tests`).

 ### Multiple Chrome Targets

 The Google Play Store allows apps to send customized bundles (`.aab` files)
 depending on the version of Android running on a device. Chrome uses this
 feature to package optimized versions for different OS versions.

 1. `monochrome_public_bundle` (`MonochromePublic.aab`)
    * `minSdkVersion=26` (Oreo).
    * Contains both Chrome and WebView (to save disk space).
 2. `trichrome_chrome_bundle` (`TrichromeChrome.aab`)
    * `minSdkVersion=29` (Android 10).
    * Native code shared with WebView through a "Static Shared Library APK": `trichrome_library_apk`
    * Corresponding WebView target: `trichrome_webview_bundle`
 3. `chrome_public_bundle` & `chrome_public_apk` (`ChromePublic.aab`, `ChromePublic.apk`)
    * `minSdkVersion=26` (Oreo).
    * Used for local development (to avoid building WebView).
    * WebView packaged independently (`system_webview_bundle` / `system_webview_apk`).

 *** note
 **Notes:**
 * These instructions use `chrome_public_apk`, but any of the other targets can
   be substituted.
 * For more about bundles, see [android_dynamic feature modules.md](android_dynamic_feature_modules.md).
 * For more about native library packaging & loading, see [android_native_libraries.md](android_native_libraries.md).
 * There are closed-source equivalents to these targets (for Googlers), which
   are identical but link in some extra code.
 ***

 ## Updating your checkout

 To update an existing checkout, you can run

 ```shell
 $ 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.

 ## Installing and Running Chromium on a device

 ### Plug in your Android device

 Make sure your Android device is plugged in via USB, and USB Debugging
 is enabled.

 To enable USB Debugging:

 *   Navigate to Settings \> About Phone \> Build number
 *   Click 'Build number' 7 times
 *   Now navigate back to Settings \> Developer Options
 *   Enable 'USB Debugging' and follow the prompts

 You may also be prompted to allow access to your PC once your device is
 plugged in.

 You can check if the device is connected by running:

 ```shell
 third_party/android_sdk/public/platform-tools/adb devices
 ```

 Which prints a list of connected devices. If not connected, try
 unplugging and reattaching your device.

 ### Enable apps from unknown sources

 Allow Android to run APKs that haven't been signed through the Play Store:

 *   Enable 'Unknown sources' under Settings \> Security

 In case that setting isn't present, it may be possible to configure it via
 `adb shell` instead:

 ```shell
 third_party/android_sdk/public/platform-tools/adb shell settings put global verifier_verify_adb_installs 0
 ```

 ### Build the full browser

 ```shell
 autoninja -C out/Default chrome_public_apk
 ```

 And deploy it to your Android device:

 ```shell
 out/Default/bin/chrome_public_apk install
 ```

 The app will appear on the device as "Chromium".

 ### Build Content shell

 Wraps the content module (but not the /chrome embedder). See
 [https://www.chromium.org/developers/content-module](https://www.chromium.org/developers/content-module)
 for details on the content module and content shell.

 ```shell
 autoninja -C out/Default content_shell_apk
 out/Default/bin/content_shell_apk install
 ```

 this will build and install an Android apk under
 `out/Default/apks/ContentShell.apk`.

 ### Build WebView

 [Android WebView](https://developer.android.com/reference/android/webkit/WebView.html)
 is a system framework component. Since Android KitKat, it is implemented using
 Chromium code (based off the [content module](https://dev.chromium.org/developers/content-module)).

 If you want to build the complete Android WebView framework component and test
 the effect of your chromium changes in Android apps using WebView, you should
 follow the [Android AOSP + chromium WebView
 instructions](https://www.chromium.org/developers/how-tos/build-instructions-android-webview)

 ### Running

 For Content shell:

 ```shell
 out/Default/bin/content_shell_apk launch [--args='--foo --bar'] http://example.com
 ```

 For Chrome public:

 ```shell
 out/Default/bin/chrome_public_apk launch [--args='--foo --bar'] http://example.com
 ```

 ### Logging and debugging

 Logging is often the easiest way to understand code flow. In C++ you can print
 log statements using the LOG macro. In Java, refer to
 [android_logging.md](android_logging.md).

 You can see these log via `adb logcat`, or:

 ```shell
 out/Default/bin/chrome_public_apk logcat
 ```

 Logcat supports an additional feature of filtering and highlighting user-defined patterns. To use
 this mechanism, define a shell variable: `CHROMIUM_LOGCAT_HIGHLIGHT` and assign your desired
 pattern. The pattern will be used to search for any substring (ie. no need to prefix or suffix it
 with `.*`), eg:

 ```shell
 export CHROMIUM_LOGCAT_HIGHLIGHT='(WARNING|cr_Child)'
 out/Default/bin/chrome_public_apk logcat
 # Highlights messages/tags containing WARNING and cr_Child strings.
 ```

 Note: both _Message_ and _Tag_ portion of logcat are matched against the pattern.

 To debug C++ code, use one of the following commands:

 ```shell
 out/Default/bin/content_shell_apk gdb
 out/Default/bin/chrome_public_apk gdb
 ```

 See [Android Debugging Instructions](android_debugging_instructions.md)
 for more on debugging, including how to debug Java code.

 ### Testing

 For information on running tests, see
 [Android Test Instructions](/docs/testing/android_test_instructions.md)

 ## Faster Builds

 ### GN Args

 Args that affect build speed:
  * `use_remoteexec = true` *(default=false)*
    * What it does: Enables distributed builds via Reclient
  * `symbol_level = 0` *(default=1)*
    * What it does: Disables debug information in native code.
    * Use this when doing primarily Java development.
    * To disable symbols only in Blink / V8: `blink_symbol_level = 0`, `v8_symbol_level = 0`
  * `is_component_build = true` *(default=`is_debug`)*
    * What it does: Uses multiple `.so` files instead of just one (faster links)
  * `is_java_debug = true` *(default=`is_debug`)*
    * What it does: Disables R8 (whole-program Java optimizer)
  * `treat_warnings_as_errors = false` *(default=`true`)*
    * Causes any compiler warnings or lint checks to not fail the build.
    * Allows you to iterate without needing to satisfy static analysis checks.
  * `android_static_analysis = "build_server"` *(default=`"on"`)*
    * Offloads static analysis steps to the build server. Explained below.
    * Set this to `"off"` if you want to turn off static analysis altogether.
  * `incremental_install = true` *(default=`false`)*
    * Makes build and install quite a bit faster. Explained in a later section.
  * `enable_chrome_android_internal = false` *(Googlers only)*
    * Disables non-public code, which exists even when building public targets.
    * Use this is you do not need to test internal-only things.

 ### Asynchronous Static Analysis

 Normally analysis build steps like Lint and Error Prone will run as normal build
 steps. The build will then wait for all analysis steps to complete successfully.
 By offloading analysis build steps to a separate build server to be run lazily at
 a low priority, the actual build can complete much faster.

 **Note**: Since the build completes before the analysis checks finish, the build
 will not fail if an analysis check fails.

 To enable this mode, add the gn args:

 ```gn
 android_static_analysis = "build_server"
 ```

 Command output will show up on the terminal that ran the build, as well as in
 `out/Debug/buildserver.log.0`.

 See the status of the server at any time via:
 ```
 build/android/fast_local_dev_server.py --print-status-all
 ```

 ### Use Reclient

 *** note
 **Warning:** If you are a Google employee, do not follow the Reclient instructions
 in this section. Set up remote execution as described in
 [go/building-android-chrome](https://goto.google.com/building-android-chrome)
 instead.
 ***

 Chromium's build can be sped up significantly by using a remote execution system
 compatible with [REAPI](https://github.com/bazelbuild/remote-apis). This allows
 you to benefit from remote caching and executing many build actions in parallel
 on a shared cluster of workers.

 To use Reclient, follow the corresponding
 [Linux build instructions](linux/build_instructions.md#use-reclient).

 ### Incremental Install
 [Incremental Install](/build/android/incremental_install/README.md) uses
 reflection and sideloading to speed up the edit & deploy cycle (normally < 10
 seconds). The initial launch of the apk will be a lot slower on older Android
 versions (pre-N) where the OS needs to pre-optimize the side-loaded files, but
 then be only marginally slower after the first launch.

 To enable Incremental Install, add the gn args:

 ```gn
 incremental_install = true
 ```

 Some APKs (e.g. WebView) do not work with `incremental install = true` and are
 always built as normal APKs. This behavior is controlled via
 `never_incremental = true`.

 ## Installing and Running Chromium on an Emulator

 Running on an emulator is the same as on a device. Refer to
 [android_emulator.md](android_emulator.md) for setting up emulators.

 ## Tips, tricks, and troubleshooting

 ### Rebuilding libchrome.so for a particular release

 These instructions are only necessary for Chrome 51 and earlier.

 In the case where you want to modify the native code for an existing
 release of Chrome for Android (v25+) you can do the following steps.
 Note that in order to get your changes into the official release, you'll
 need to send your change for a codereview using the regular process for
 committing code to chromium.

 1.  Open Chrome on your Android device and visit chrome://version
 2.  Copy down the id listed next to "Build ID:"
 3.  Go to
     [http://storage.googleapis.com/chrome-browser-components/BUILD\_ID\_FROM\_STEP\_2/index.html](http://storage.googleapis.com/chrome-browser-components/BUILD_ID_FROM_STEP_2/index.html)
 4.  Download the listed files and follow the steps in the README.

 ### Building with Docker

 To build Chromium for Android using Docker, please follow the
 instructions in the [Docker in Linux build instructions](/docs/linux/build_instructions.md#docker).

 *** note
 **Note:** You need install the [Android dependencies](#install-additional-build-dependencies) after setting up the [Build dependencies](/docs/linux/build_instructions.md#install-additional-build-dependencies).
 ***
	# Checking out and building Chromium for Android

	There are instructions for other platforms linked from the
	[get the code](get_the_code.md) page.

	## Instructions for Google Employees

	Are you a Google employee? See
	[go/building-android-chrome](https://goto.google.com/building-android-chrome)
	instead.

	[TOC]

	## System requirements

	* An x86-64 machine running Linux with at least 8GB of RAM. More than 16GB is
	highly recommended.
	* At least 100GB of free disk space.
	* You must have Git and Python installed already.

	Most development is done on Ubuntu. Other distros may or may not work;
	see the [Linux instructions](linux/build_instructions.md) for some suggestions.

	Building the Android client on Windows or Mac is not supported and doesn't work.

	## Install depot\_tools

	Clone the `depot_tools` repository:

	```shell
	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`:

	```shell
	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):

	```shell
	mkdir ~/chromium && cd ~/chromium
	fetch --nohooks android
	```

	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.

	If you've already installed the build dependencies on the machine (from another
	checkout, for example), you can omit the `--nohooks` flag and `fetch`
	will automatically execute `gclient runhooks` at the end.

	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:

	```shell
	cd src
	```

	### Converting an existing Linux checkout

	If you have an existing Linux checkout, you can add Android support by
	appending `target_os = ['linux', 'android']` to your `.gclient` file (in the
	directory above `src`):

	```shell
	echo "target_os = [ 'linux', 'android' ]" >> ../.gclient
	```

	Then run `gclient sync` to pull the new Android dependencies:

	```shell
	gclient sync
	```

	(This is the only difference between `fetch android` and `fetch chromium`.)

	### Install additional build dependencies

	Once you have checked out the code, run

	```shell
	build/install-build-deps.sh
	```

	to get all of the dependencies you need to build on Linux, plus all of the
	Android-specific dependencies (you need some of the regular Linux dependencies
	because an Android build includes a bunch of the Linux tools and utilities).

	NOTE: For 32-bit builds, the `--lib32` command line switch could be used.
	You may run into issues where `gperf` or `pkgconf` don't get installed,
	without it. To remedy this, and potentially other missing packages, you will
	have to install them manually using:

	```shell
	sudo apt-get install {missing_pkg}
	```

	### Run the hooks

	Once you've run `install-build-deps` at least once, you can now run the
	Chromium-specific hooks, which will download additional binaries and other
	things you might need:

	```shell
	gclient runhooks
	```

	Optional: You can also [install API
	keys](https://www.chromium.org/developers/how-tos/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

	Chromium uses [Ninja](https://ninja-build.org) as its main build tool along with
	a tool called [GN](https://gn.googlesource.com/gn/+/main/docs/quick_start.md)
	to generate `.ninja` files. You can create any number of build directories
	with different configurations. To create a build directory which builds Chrome
	for Android, run `gn args out/Default` and edit the file to contain the
	following arguments:

	```gn
	target_os = "android"
	target_cpu = "arm64" # See "Figuring out target_cpu" below
	use_remoteexec = true # Enables distributed builds. See "Faster Builds".
	android_static_analysis = "build_server" # Does static checks in background. See "Faster Builds".
	```

	* You only have to run this once for each new build directory, Ninja will
	update the build files as needed.
	* You can replace `Default` with another name, but
	it should be a subdirectory of `out`.
	* For other build arguments, including release settings, see [GN build
	configuration](https://www.chromium.org/developers/gn-build-configuration).
	The default will be a debug component build.
	* For more info on GN, run `gn help` on the command line or read the
	[quick start guide](https://gn.googlesource.com/gn/+/main/docs/quick_start.md).

	Also be aware that some scripts (e.g. `tombstones.py`, `adb_gdb.py`)
	require you to set `CHROMIUM_OUTPUT_DIR=out/Default`.

	### Figuring out target\_cpu

	The value of
	[`target_cpu`](https://gn.googlesource.com/gn/+/main/docs/reference.md#var_target_cpu)
	determines what instruction set to use for native code. Given a device (or
	emulator), you can determine the correct instruction set with `adb shell getprop
	ro.product.cpu.abi`:

	\| `getprop ro.product.cpu.abi` output \| `target_cpu` value \|
	\|-------------------------------------\|--------------------\|
	\| `arm64-v8a` \| `arm64` \|
	\| `armeabi-v7a` \| `arm` \|
	\| `x86` \| `x86` \|
	\| `x86_64` \| `x64` \|

	*** promo
	`arm` and `x86` may optionally be used instead of `arm64` and `x64` for
	non-WebView targets. This is also allowed for Monochrome, but only when not set
	as the WebView provider.
	***

	## Build Chromium

	Build Chromium with Ninja using the command:

	```shell
	autoninja -C out/Default chrome_public_apk
	```

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

	You can get a list of all of the other build targets from GN by running `gn ls
	out/Default` from the command line. To compile one, pass the GN label to Ninja
	with no preceding "//" (so, for `//chrome/test:unit_tests` use `autoninja -C
	out/Default chrome/test:unit_tests`).

	### Multiple Chrome Targets

	The Google Play Store allows apps to send customized bundles (`.aab` files)
	depending on the version of Android running on a device. Chrome uses this
	feature to package optimized versions for different OS versions.

	1. `monochrome_public_bundle` (`MonochromePublic.aab`)
	* `minSdkVersion=26` (Oreo).
	* Contains both Chrome and WebView (to save disk space).
	2. `trichrome_chrome_bundle` (`TrichromeChrome.aab`)
	* `minSdkVersion=29` (Android 10).
	* Native code shared with WebView through a "Static Shared Library APK": `trichrome_library_apk`
	* Corresponding WebView target: `trichrome_webview_bundle`
	3. `chrome_public_bundle` & `chrome_public_apk` (`ChromePublic.aab`, `ChromePublic.apk`)
	* `minSdkVersion=26` (Oreo).
	* Used for local development (to avoid building WebView).
	* WebView packaged independently (`system_webview_bundle` / `system_webview_apk`).

	*** note
	Notes:
	* These instructions use `chrome_public_apk`, but any of the other targets can
	be substituted.
	* For more about bundles, see [android_dynamic feature modules.md](android_dynamic_feature_modules.md).
	* For more about native library packaging & loading, see [android_native_libraries.md](android_native_libraries.md).
	* There are closed-source equivalents to these targets (for Googlers), which
	are identical but link in some extra code.
	***

	## Updating your checkout

	To update an existing checkout, you can run

	```shell
	$ 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.

	## Installing and Running Chromium on a device

	### Plug in your Android device

	Make sure your Android device is plugged in via USB, and USB Debugging
	is enabled.

	To enable USB Debugging:

	* Navigate to Settings \> About Phone \> Build number
	* Click 'Build number' 7 times
	* Now navigate back to Settings \> Developer Options
	* Enable 'USB Debugging' and follow the prompts

	You may also be prompted to allow access to your PC once your device is
	plugged in.

	You can check if the device is connected by running:

	```shell
	third_party/android_sdk/public/platform-tools/adb devices
	```

	Which prints a list of connected devices. If not connected, try
	unplugging and reattaching your device.

	### Enable apps from unknown sources

	Allow Android to run APKs that haven't been signed through the Play Store:

	* Enable 'Unknown sources' under Settings \> Security

	In case that setting isn't present, it may be possible to configure it via
	`adb shell` instead:

	```shell
	third_party/android_sdk/public/platform-tools/adb shell settings put global verifier_verify_adb_installs 0
	```

	### Build the full browser

	```shell
	autoninja -C out/Default chrome_public_apk
	```

	And deploy it to your Android device:

	```shell
	out/Default/bin/chrome_public_apk install
	```

	The app will appear on the device as "Chromium".

	### Build Content shell

	Wraps the content module (but not the /chrome embedder). See
	[https://www.chromium.org/developers/content-module](https://www.chromium.org/developers/content-module)
	for details on the content module and content shell.

	```shell
	autoninja -C out/Default content_shell_apk
	out/Default/bin/content_shell_apk install
	```

	this will build and install an Android apk under
	`out/Default/apks/ContentShell.apk`.

	### Build WebView

	[Android WebView](https://developer.android.com/reference/android/webkit/WebView.html)
	is a system framework component. Since Android KitKat, it is implemented using
	Chromium code (based off the [content module](https://dev.chromium.org/developers/content-module)).

	If you want to build the complete Android WebView framework component and test
	the effect of your chromium changes in Android apps using WebView, you should
	follow the [Android AOSP + chromium WebView
	instructions](https://www.chromium.org/developers/how-tos/build-instructions-android-webview)

	### Running

	For Content shell:

	```shell
	out/Default/bin/content_shell_apk launch [--args='--foo --bar'] http://example.com
	```

	For Chrome public:

	```shell
	out/Default/bin/chrome_public_apk launch [--args='--foo --bar'] http://example.com
	```

	### Logging and debugging

	Logging is often the easiest way to understand code flow. In C++ you can print
	log statements using the LOG macro. In Java, refer to
	[android_logging.md](android_logging.md).

	You can see these log via `adb logcat`, or:

	```shell
	out/Default/bin/chrome_public_apk logcat
	```

	Logcat supports an additional feature of filtering and highlighting user-defined patterns. To use
	this mechanism, define a shell variable: `CHROMIUM_LOGCAT_HIGHLIGHT` and assign your desired
	pattern. The pattern will be used to search for any substring (ie. no need to prefix or suffix it
	with `.*`), eg:

	```shell
	export CHROMIUM_LOGCAT_HIGHLIGHT='(WARNING\|cr_Child)'
	out/Default/bin/chrome_public_apk logcat
	# Highlights messages/tags containing WARNING and cr_Child strings.
	```

	Note: both _Message_ and _Tag_ portion of logcat are matched against the pattern.

	To debug C++ code, use one of the following commands:

	```shell
	out/Default/bin/content_shell_apk gdb
	out/Default/bin/chrome_public_apk gdb
	```

	See [Android Debugging Instructions](android_debugging_instructions.md)
	for more on debugging, including how to debug Java code.

	### Testing

	For information on running tests, see
	[Android Test Instructions](/docs/testing/android_test_instructions.md)

	## Faster Builds

	### GN Args

	Args that affect build speed:
	* `use_remoteexec = true` (default=false)
	* What it does: Enables distributed builds via Reclient
	* `symbol_level = 0` (default=1)
	* What it does: Disables debug information in native code.
	* Use this when doing primarily Java development.
	* To disable symbols only in Blink / V8: `blink_symbol_level = 0`, `v8_symbol_level = 0`
	* `is_component_build = true` (default=`is_debug`)
	* What it does: Uses multiple `.so` files instead of just one (faster links)
	* `is_java_debug = true` (default=`is_debug`)
	* What it does: Disables R8 (whole-program Java optimizer)
	* `treat_warnings_as_errors = false` (default=`true`)
	* Causes any compiler warnings or lint checks to not fail the build.
	* Allows you to iterate without needing to satisfy static analysis checks.
	* `android_static_analysis = "build_server"` (default=`"on"`)
	* Offloads static analysis steps to the build server. Explained below.
	* Set this to `"off"` if you want to turn off static analysis altogether.
	* `incremental_install = true` (default=`false`)
	* Makes build and install quite a bit faster. Explained in a later section.
	* `enable_chrome_android_internal = false` (Googlers only)
	* Disables non-public code, which exists even when building public targets.
	* Use this is you do not need to test internal-only things.

	### Asynchronous Static Analysis

	Normally analysis build steps like Lint and Error Prone will run as normal build
	steps. The build will then wait for all analysis steps to complete successfully.
	By offloading analysis build steps to a separate build server to be run lazily at
	a low priority, the actual build can complete much faster.

	Note: Since the build completes before the analysis checks finish, the build
	will not fail if an analysis check fails.

	To enable this mode, add the gn args:

	```gn
	android_static_analysis = "build_server"
	```

	Command output will show up on the terminal that ran the build, as well as in
	`out/Debug/buildserver.log.0`.

	See the status of the server at any time via:
	```
	build/android/fast_local_dev_server.py --print-status-all
	```

	### Use Reclient

	*** note
	Warning: If you are a Google employee, do not follow the Reclient instructions
	in this section. Set up remote execution as described in
	[go/building-android-chrome](https://goto.google.com/building-android-chrome)
	instead.
	***

	Chromium's build can be sped up significantly by using a remote execution system
	compatible with [REAPI](https://github.com/bazelbuild/remote-apis). This allows
	you to benefit from remote caching and executing many build actions in parallel
	on a shared cluster of workers.

	To use Reclient, follow the corresponding
	[Linux build instructions](linux/build_instructions.md#use-reclient).

	### Incremental Install
	[Incremental Install](/build/android/incremental_install/README.md) uses
	reflection and sideloading to speed up the edit & deploy cycle (normally < 10
	seconds). The initial launch of the apk will be a lot slower on older Android
	versions (pre-N) where the OS needs to pre-optimize the side-loaded files, but
	then be only marginally slower after the first launch.

	To enable Incremental Install, add the gn args:

	```gn
	incremental_install = true
	```

	Some APKs (e.g. WebView) do not work with `incremental install = true` and are
	always built as normal APKs. This behavior is controlled via
	`never_incremental = true`.

	## Installing and Running Chromium on an Emulator

	Running on an emulator is the same as on a device. Refer to
	[android_emulator.md](android_emulator.md) for setting up emulators.

	## Tips, tricks, and troubleshooting

	### Rebuilding libchrome.so for a particular release

	These instructions are only necessary for Chrome 51 and earlier.

	In the case where you want to modify the native code for an existing
	release of Chrome for Android (v25+) you can do the following steps.
	Note that in order to get your changes into the official release, you'll
	need to send your change for a codereview using the regular process for
	committing code to chromium.

	1. Open Chrome on your Android device and visit chrome://version
	2. Copy down the id listed next to "Build ID:"
	3. Go to
	[http://storage.googleapis.com/chrome-browser-components/BUILD\_ID\_FROM\_STEP\_2/index.html](http://storage.googleapis.com/chrome-browser-components/BUILD_ID_FROM_STEP_2/index.html)
	4. Download the listed files and follow the steps in the README.

	### Building with Docker

	To build Chromium for Android using Docker, please follow the
	instructions in the [Docker in Linux build instructions](/docs/linux/build_instructions.md#docker).

	*** note
	Note: You need install the [Android dependencies](#install-additional-build-dependencies) after setting up the [Build dependencies](/docs/linux/build_instructions.md#install-additional-build-dependencies).
	***