Move the job scheduler service code to its own jar file.

# Making Job Scheduler into a Mainline Module

## TODOs

See also:

- http://go/moving-js-code-for-mainline

- http://go/jobscheduler-code-dependencies-2019-07

- [ ] Move client code

  - [ ] Move code

  - [ ] Make build file

  - [ ] "m jobscheduler-framework" pass

  - [ ] "m framework" pass

  - [ ] "m service" pass

- [ ] Move proto

  - No, couldn't do it, because it's referred to by incidentd_proto

- [ ] Move service

  - [X] Move code (done, but it won't compile yet)

  - [X] Make build file

  - [X] "m service" pass

  - [X] "m jobscheduler-service" pass

    - To make it pass, jobscheduler-service has to link services.jar too. Many dependencies.

- [ ] Move this into `frameworks/apex/jobscheduler/...`. Currently it's in `frameworks/base/apex/...`

because `frameworks/apex/` is not a part of any git projects. (and also working on multiple

projects is a pain.)

## Problems

- Couldn't move dumpsys proto files. They are used by incidentd_proto, which is in the platform

  (not updatable).

  - One idea is *not* to move the proto files into apex but keep them in the platform.

    Then we make sure to extend the proto files in a backward-compat way (which we do anyway)

    and always use the latest file from the JS apex.

- There are a lot of build tasks that use "framework.jar". (Examples: hiddenapi-greylist.txt check,

  update-api / public API check and SDK stub (android.jar) creation)

  To make the downstream build modules buildable, we need to include js-framework.jar in

  framework.jar. However it turned out to be tricky because soong has special logic for "framework"

  and "framework.jar".

  i.e. Conceptually, we can do it by renaming `framework` to `framework-minus-jobscheduler`, build

  `jobscheduler-framework` with `framework-minus-jobscheduler`, and create `framework` by merging

  `framework-minus-jobscheduler` and `jobscheduler-framework`.

  However it didn't quite work because of the special casing.

- JS-service uses a lot of other code in `services`, so it needs to link services.core.jar e.g.

 - Common system service code, e.g. `com.android.server.SystemService`

 - Common utility code, e.g. `FgThread` and `IoThread`

 - Other system services such as `DeviceIdleController` and `ActivityManagerService`

 - Server side singleton. `AppStateTracker`

 - `DeviceIdleController.LocalService`, which is a local service but there's no interface class.

 - `XxxInternal` interfaces that are not in the framework side. -> We should be able to move them.

// Job Scheduler Service jar, which will eventually be put in the jobscheduler mainline apex.

// jobscheduler-service needs to be added to PRODUCT_SYSTEM_SERVER_JARS.

java_library {

    name: "jobscheduler-service",

    installable: true,

    srcs: [

        "java/**/*.java",

    ],

    libs: [

        "framework",

        "services.core",

    ],

}