feat: preloads and nodeIntegration in iframes (#16425)

* feat: add support for node / preloads in subframes

This feature has delibrately been built / implemented in such a way
that it has minimum impact on existing apps / code-paths.
Without enabling the new "nodeSupportInSubFrames" option basically none of this
new code will be hit.

The things that I believe need extra scrutiny are:

* Introduction of `event.reply` for IPC events and usage of `event.reply` instead of `event.sender.send()`
* Usage of `node::FreeEnvironment(env)` when the new option is enabled in order to avoid memory leaks.  I have tested this quite a bit and haven't managed to cause a crash but it is still feature flagged behind the "nodeSupportInSubFrames" flag to avoid potential impact.

Closes #10569
Closes #10401
Closes #11868
Closes #12505
Closes #14035

* feat: add support preloads in subframes for sandboxed renderers

* spec: add tests for new nodeSupportInSubFrames option

* spec: fix specs for .reply and ._replyInternal for internal messages

* chore: revert change to use flag instead of environment set size

* chore: clean up subframe impl

* chore: apply suggestions from code review

Co-Authored-By: MarshallOfSound <samuel.r.attard@gmail.com>

* chore: clean up reply usage

* chore: fix TS docs generation

* chore: cleanup after rebase

* chore: rename wrap to add in event fns

spec/api-subframe-spec.js

@@ -0,0 +1,88 @@
+const { expect } = require('chai')
+const { remote } = require('electron')
+const path = require('path')
+
+const { emittedNTimes, emittedOnce } = require('./events-helpers')
+const { closeWindow } = require('./window-helpers')
+
+const { BrowserWindow } = remote
+
+describe('renderer nodeIntegrationInSubFrames', () => {
+  const generateTests = (sandboxEnabled) => {
+    describe(`with sandbox ${sandboxEnabled ? 'enabled' : 'disabled'}`, () => {
+      let w
+
+      beforeEach(async () => {
+        await closeWindow(w)
+        w = new BrowserWindow({
+          show: false,
+          width: 400,
+          height: 400,
+          webPreferences: {
+            sandbox: sandboxEnabled,
+            preload: path.resolve(__dirname, 'fixtures/sub-frames/preload.js'),
+            nodeIntegrationInSubFrames: true
+          }
+        })
+      })
+
+      afterEach(() => {
+        return closeWindow(w).then(() => { w = null })
+      })
+
+      it('should load preload scripts in top level iframes', async () => {
+        const detailsPromise = emittedNTimes(remote.ipcMain, 'preload-ran', 2)
+        w.loadFile(path.resolve(__dirname, 'fixtures/sub-frames/frame-container.html'))
+        const [event1, event2] = await detailsPromise
+        expect(event1[0].frameId).to.not.equal(event2[0].frameId)
+        expect(event1[0].frameId).to.equal(event1[2])
+        expect(event2[0].frameId).to.equal(event2[2])
+      })
+
+      it('should load preload scripts in nested iframes', async () => {
+        const detailsPromise = emittedNTimes(remote.ipcMain, 'preload-ran', 3)
+        w.loadFile(path.resolve(__dirname, 'fixtures/sub-frames/frame-with-frame-container.html'))
+        const [event1, event2, event3] = await detailsPromise
+        expect(event1[0].frameId).to.not.equal(event2[0].frameId)
+        expect(event1[0].frameId).to.not.equal(event3[0].frameId)
+        expect(event2[0].frameId).to.not.equal(event3[0].frameId)
+        expect(event1[0].frameId).to.equal(event1[2])
+        expect(event2[0].frameId).to.equal(event2[2])
+        expect(event3[0].frameId).to.equal(event3[2])
+      })
+
+      it('should correctly reply to the main frame with using event.reply', async () => {
+        const detailsPromise = emittedNTimes(remote.ipcMain, 'preload-ran', 2)
+        w.loadFile(path.resolve(__dirname, 'fixtures/sub-frames/frame-container.html'))
+        const [event1] = await detailsPromise
+        const pongPromise = emittedOnce(remote.ipcMain, 'preload-pong')
+        event1[0].reply('preload-ping')
+        const details = await pongPromise
+        expect(details[1]).to.equal(event1[0].frameId)
+      })
+
+      it('should correctly reply to the sub-frames with using event.reply', async () => {
+        const detailsPromise = emittedNTimes(remote.ipcMain, 'preload-ran', 2)
+        w.loadFile(path.resolve(__dirname, 'fixtures/sub-frames/frame-container.html'))
+        const [, event2] = await detailsPromise
+        const pongPromise = emittedOnce(remote.ipcMain, 'preload-pong')
+        event2[0].reply('preload-ping')
+        const details = await pongPromise
+        expect(details[1]).to.equal(event2[0].frameId)
+      })
+
+      it('should correctly reply to the nested sub-frames with using event.reply', async () => {
+        const detailsPromise = emittedNTimes(remote.ipcMain, 'preload-ran', 3)
+        w.loadFile(path.resolve(__dirname, 'fixtures/sub-frames/frame-with-frame-container.html'))
+        const [,, event3] = await detailsPromise
+        const pongPromise = emittedOnce(remote.ipcMain, 'preload-pong')
+        event3[0].reply('preload-ping')
+        const details = await pongPromise
+        expect(details[1]).to.equal(event3[0].frameId)
+      })
+    })
+  }
+
+  generateTests(false)
+  generateTests(true)
+})