This directory contains low-level support for Chrome running on Chrome OS. 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. For example, //chromeos/components/account_manager manages the user's GAIA accounts, but is used as the backend for UI that only exists on Chrome OS devices.
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.