This directory contains low-level support for Chrome running on Chrome OS.
The Lacros project is in the process of extracting the browser-functionality into a separate binary. This introduces the following terminology and rules:
- ash-chrome: The new name of the legacy “chrome” binary. It contains system UI and the current/legacy web browser. Code that is only used by ash-chrome should eventually be moved to //ash, have an _ash suffix in the filename, or have a (grand-)parent directory named /ash/.
- lacros-chrome: The name of the new, standalone web-browser binary. Code that is only used by lacros-chrome should have a _lacros suffix in the filename, or have a (grand-)parent directory named /lacros/.
- crosapi: The term “crosapi” is short for ChromeOS API. Ash-chrome implements the API, and lacros-chrome is the only consumer.
- chromeos: The term “chromeos” refers to code that is shared by binaries targeting the chromeos platform or using the chromeos toolchain. Code that is shared by ash-chrome and lacros-chrome should have a _chromeos suffix in the filename, or have a (grand-)parent directory named /chromeos/.
- Exception: The exception to the rule is //chrome/browser/chromeos. Following existing conventions in //chrome, the directory should refer to lacros-chrome. However, this would involve a massive and otherwise unnecessary refactor. //chrome/browser/chromeos will continue to contain code that is only used by ash-chrome. //chrome/browser/lacros will contain code used only by lacros-chrome. See this document for more details.
Many subdirectories contain Chrome-style C++ wrappers around operating system components.
For example, //chromeos/dbus contains wrappers around the D-Bus interfaces to system daemons like the network configuration manager (shill). Most other directories contain low-level utility code. For example, //chromeos/disks has utilities for mounting and unmounting disk volumes.
There are two exceptions:
//chromeos/services contains mojo services that were not considered sufficiently general to live in top-level //services. For example //chromeos/services/secure_channel bootstraps a secure communications channel to an Android phone over Bluetooth, enabling multi-device features like instant tethering.
//chromeos/components contains C++ components that were not considered sufficiently general to live in top-level //components.
Note, //chromeos does not contain any user-facing UI code, and hence it has “-ui” in its DEPS. The contents of //chromeos should also not depend on //chrome or //content.