Checking out and building Cast for Android

Note: it is not possible to build a binary functionally equivalent to a Chromecast. This is to build a single-page content embedder with similar functionality to Cast products.

Instructions for Google Employees

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

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 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:

$ 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
$ 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:

$ cd src

Converting an existing Linux checkout

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

$ echo "target_os = [ 'android' ]" >> ../.gclient

Then run gclient sync to pull the new Android dependencies:

$ 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

$ build/install-build-deps.sh --android

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).

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:

$ gclient runhooks

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

Chromium uses Ninja as its main build tool along with a tool called GN 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 gen --args='target_os="android" is_cast_android=true' out/Default
  • 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. The default will be a debug component build matching the current host operating system and CPU.
  • For more info on GN, run gn help on the command line or read the quick start guide.

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

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

Warning: If you are a Google employee, do not follow the instructions below. See go/building-android-chrome#initialize-remote-execution-distributed-builds instead.

Chromium's build can be sped up significantly by using a remote execution system compatible with REAPI. 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.

Build cast_shell_apk

Build cast_shell_apk with Ninja using the command:

$ autoninja -C out/Default cast_shell_apk

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

Installing and Running cast_shell_apk 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:

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.

Build the APK

autoninja -C out/Release cast_shell_apk

And deploy it to your Android device:

out/Default/bin/cast_shell_apk install
# Or to install and run:
out/Default/bin/cast_shell_apk run "http://google.com"

The app will appear on the device as “Chromium”.

Testing

For information on running tests, see Android Test Instructions.