feat: redesign preload APIs (#45329)

* feat: redesign preload APIs

Co-authored-by: Samuel Maddock <samuel.maddock@gmail.com>

* docs: remove service-worker mentions for now

Co-authored-by: Samuel Maddock <samuel.maddock@gmail.com>

* fix lint

Co-authored-by: Samuel Maddock <samuel.maddock@gmail.com>

* remove service-worker ipc code

Co-authored-by: Samuel Maddock <samuel.maddock@gmail.com>

* add filename

Co-authored-by: Samuel Maddock <samuel.maddock@gmail.com>

* fix: web preferences preload not included

Co-authored-by: Samuel Maddock <samuel.maddock@gmail.com>

* fix: missing common init

Co-authored-by: Samuel Maddock <samuel.maddock@gmail.com>

* fix: preload bundle script error

Co-authored-by: Samuel Maddock <samuel.maddock@gmail.com>

---------

Co-authored-by: trop[bot] <37223003+trop[bot]@users.noreply.github.com>
Co-authored-by: Samuel Maddock <samuel.maddock@gmail.com>

docs/api/session.md

@@ -1330,18 +1330,43 @@ the initial state will be `interrupted`. The download will start only when the
 
 Returns `Promise<void>` - resolves when the session’s HTTP authentication cache has been cleared.
 
-#### `ses.setPreloads(preloads)`
+#### `ses.setPreloads(preloads)` _Deprecated_
 
 * `preloads` string[] - An array of absolute path to preload scripts
 
 Adds scripts that will be executed on ALL web contents that are associated with
 this session just before normal `preload` scripts run.
 
-#### `ses.getPreloads()`
+**Deprecated:** Use the new `ses.registerPreloadScript` API.
+
+#### `ses.getPreloads()` _Deprecated_
 
 Returns `string[]` an array of paths to preload scripts that have been
 registered.
 
+**Deprecated:** Use the new `ses.getPreloadScripts` API. This will only return preload script paths
+for `frame` context types.
+
+#### `ses.registerPreloadScript(script)`
+
+* `script` [PreloadScriptRegistration](structures/preload-script-registration.md) - Preload script
+
+Registers preload script that will be executed in its associated context type in this session. For
+`frame` contexts, this will run prior to any preload defined in the web preferences of a
+WebContents.
+
+Returns `string` - The ID of the registered preload script.
+
+#### `ses.unregisterPreloadScript(id)`
+
+* `id` string - Preload script ID
+
+Unregisters script.
+
+#### `ses.getPreloadScripts()`
+
+Returns [`PreloadScript[]`](structures/preload-script.md): An array of paths to preload scripts that have been registered.
+
 #### `ses.setCodeCachePath(path)`
 
 * `path` String - Absolute path to store the v8 generated JS code cache from the renderer.

docs/api/structures/preload-script-registration.md

@@ -0,0 +1,6 @@
+# PreloadScriptRegistration Object
+
+* `type` string - Context type where the preload script will be executed.
+  Possible values include `frame`.
+* `id` string (optional) - Unique ID of preload script. Defaults to a random UUID.
+* `filePath` string - Path of the script file. Must be an absolute path.

docs/api/structures/preload-script.md

@@ -0,0 +1,6 @@
+# PreloadScript Object
+
+* `type` string - Context type where the preload script will be executed.
+  Possible values include `frame`.
+* `id` string - Unique ID of preload script.
+* `filePath` string - Path of the script file. Must be an absolute path.

docs/breaking-changes.md

@@ -14,6 +14,25 @@ This document uses the following convention to categorize breaking changes:
 
 ## Planned Breaking API Changes (35.0)
 
+### Deprecated: `setPreloads`, `getPreloads` on `Session`
+
+`registerPreloadScript`, `unregisterPreloadScript`, and `getPreloadScripts` are introduced as a
+replacement for the deprecated methods. These new APIs allow third-party libraries to register
+preload scripts without replacing existing scripts. Also, the new `type` option allows for
+additional preload targets beyond `frame`.
+
+```ts
+// Deprecated
+session.setPreloads([path.join(__dirname, 'preload.js')])
+
+// Replace with:
+session.registerPreloadScript({
+  type: 'frame',
+  id: 'app-preload',
+  filePath: path.join(__dirname, 'preload.js')
+})
+```
+
 ### Deprecated: `level`, `message`, `line`, and `sourceId` arguments in `console-message` event on `WebContents`
 
 The `console-message` event on `WebContents` has been updated to provide details on the `Event`