Chromium recipe
===============

This recipe provides a package for the Chromium web browser. It strives to
always follow the latest stable Linux release as listed in
https://omahaproxy.appspot.com

We refer to the web browser as Chromium, not Chrome, because "Chrome" is
Google's version of the web browser with proprietary content on top of the
open-source Chromium browser.

Compared to a usual, smaller recipe, the Chromium recipe has a few
peculiarities:
- We manually patch parts of the build system to replace Chromium's bundled
  copies of some packages (flac, libjpeg and others) with system-wide ones.
- Parts of the V8 (Chromium's JavaScript engine) build need to run binaries
  built for the target, for which we use QEMU.

Build requirements
------------------
This recipe requires clang, and GCC is not supported. Upstream Chromium has not
tested or officially supported GCC for years, so it is safer and easier to
follow their lead and only support one compiler.

As part of its build process, Chromium builds and runs some binaries on the
host. clang-native from the meta-clang layer is used to build those binaries.

For building most of the code for your target, a C++14-compliant compiler is
required. At least clang 7.0.0 (and thus the "thud" branch) is required.

Additionally, make sure the machine being used to build Chromium is powerful
enough: a x86-64 machine with at least 16GB RAM is recommended.

PACKAGECONFIG knobs
-------------------
* component-build: (off by default)
  Enables component build mode. By default, all of Chromium (with the exception
  of FFmpeg) is linked into one big binary. The linker step requires at least 8
  GB RAM. Component mode was created to facilitate development and testing,
  since with it, there is not one big binary; instead, each component is linked
  to a separate shared object. Use component mode for development, testing, and
  in case the build machine is not a 64-bit one, or has less than 8 GB RAM.

* cups: (off by default)
  Enables CUPS support in Chromium, and adds a dependency on the "cups" recipe.

* impl-side-painting: (off by default)
  This is a new painting mechanism. Still in development stages, it can improve
  performance See
  http://www.chromium.org/developers/design-documents/impl-side-painting for
  more.

* jumbo-build: (off by default)
  Enables what's also known as "unity builds": several source files are merged
  together and compiled only once in order to reduce build times, but may end
  up requiring more memory at certain points.

  Jumbo builds are documented here:
  https://chromium.googlesource.com/chromium/src/+/master/docs/jumbo.md

* kiosk-mode: (off by default)
  Enable this option if you want your browser to start up full-screen, without
  any menu bars, without any clutter, and without any initial start-up
  indicators.

* proprietary-codecs: (off by default)
  Enable this option if you want to add support for additional proprietary
  codecs, most notably MPEG standards (h.264, h.265, MP4, MP3, AAC etc). It is
  your responsibility to make sure you are complying with the codecs' licensing
  terms.

* use-egl: (on by default)
  Without this packageconfig, the Chromium build will use GLX for creating an
  OpenGL context in X11, and regular OpenGL for painting operations. Neither
  are desirable on embedded platforms. With this packageconfig, EGL and OpenGL
  ES 2.x are used instead.

Google API keys
---------------
Some Chromium features use Google APIs, and to access those APIs either an API
Key or a set of OAuth 2.0 tokens is required. Setting up API keys is optional.

If you don't do it, the specific APIs using Google services won't work in your
build, but all other features will run normally.

By default, we build Chromium with invalid keys to avoid the "Google API keys
are missing" error message in the browser's infobar. If you have your own API
keys, you need to set the GOOGLE_API_KEY, GOOGLE_DEFAULT_CLIENT_ID and
GOOGLE_DEFAULT_CLIENT_SECRET appropriately in your local.conf.

For more information, see https://dev.chromium.org/developers/how-tos/api-keys.
