docs-bug(cdk/layout): LayoutModule is not needed

[gultyayev]

Documentation Feedback

In the docs it's mentioned that we need to import LayoutModule in order to use BreakpointObserver and MediaMatcher.
In the meantime from the source code it looks like the module is not needed for any purposes.

Affected documentation page

https://material.angular.io/cdk/layout/api

[crisbeto]

I think that this is a leftover from before providedIn: 'root' existed.

[gultyayev]

Perhaps it's worth using "providedIn: LayoutModule" so the services could be included in lazy loaded modules only instead of the app module?

[crisbeto]

These services were always intended to be global so that the cached state can be reused as much as possible.

[gultyayev]

I get that. However if you use providedIn: Module the service isn't re-created. The instance will be shared and it won't appear in the initial bundle if was used in lazy loaded modules only

[crisbeto]

The same is true for providedIn: 'root' which the services are using.

[gultyayev]

Not quite. If I use it in lazy loaded module only it will increase my initial bundle size.

[crisbeto]

That's not how it works though. providedIn: 'root' means that it'll be pulled in only into the bundles that use it. If it's ending up in your initial bundle, it's likely being used across multiple lazy-loaded bundles.

[gultyayev]

However, webpack is capable of making a chunk shared across other lazy loaded chunks.