$ gn gen out/Default --args='root_extra_deps=["//electron"] is_electron_build=true is_component_build=true use_jumbo_build=true v8_promise_internal_field_count=1 v8_typed_array_max_size_in_heap=0'
```
This will generate all the ninja files needed for the build. You shouldn't have
to run `gn gen` again—if you want to change the build arguments you can run `gn
args out/Default` to bring up an editor.
To build, run `ninja` with the `electron:electron_app` target:
```sh
$ ninja -C out/Default electron:electron_app
# This will also take a while and probably heat up your lap.
```
This will build all of what was previously 'libchromiumcontent' (i.e. the
`content/` directory of `chromium` and its dependencies, incl. WebKit and V8),
so it will take a while.
To speed up subsequent builds, you can use [sccache][sccache]. Add the GN arg
`cc_wrapper="sccache"` by running `gn args out/Default` to bring up an editor.
[sccache]: https://github.com/mozilla/sccache
The built executable will be under `./out/Default`: