Chromium is the open-source version of Google Chrome. Fixes T233
Notes of interest:
* Widevine support is enabled but not shipped due to legal reasons,
you can copy `libwidevinecdm.so` from google-chrome to enable it.
* There is no support for Adobe Flash
* In the future a remoting desktop subpackage will be provided (T1912)
* A headless_shell subpackage for developers is also planned
in the future.