feat: add chrome.runtime.getManifest (#16891)

* feat: add chrome.runtime.getManifest

* Add test for chrome.runtime.getManifest

* Use IPC utils for getManifest internals

spec/chrome-api-spec.js

@@ -0,0 +1,48 @@
+const fs = require('fs')
+const path = require('path')
+
+const { expect } = require('chai')
+const { remote } = require('electron')
+
+const { closeWindow } = require('./window-helpers')
+const { emittedOnce } = require('./events-helpers')
+
+const { BrowserWindow } = remote
+
+describe('chrome api', () => {
+  const fixtures = path.resolve(__dirname, 'fixtures')
+  let w
+
+  before(() => {
+    BrowserWindow.addExtension(path.join(fixtures, 'extensions/chrome-api'))
+  })
+
+  after(() => {
+    BrowserWindow.removeExtension('chrome-api')
+  })
+
+  beforeEach(() => {
+    w = new BrowserWindow({
+      show: false
+    })
+  })
+
+  afterEach(() => closeWindow(w).then(() => { w = null }))
+
+  it('runtime.getManifest returns extension manifest', async () => {
+    const actualManifest = (() => {
+      const data = fs.readFileSync(path.join(fixtures, 'extensions/chrome-api/manifest.json'), 'utf-8')
+      return JSON.parse(data)
+    })()
+
+    w.loadURL('about:blank')
+
+    const p = emittedOnce(w.webContents, 'console-message')
+    w.webContents.executeJavaScript(`window.postMessage('getManifest', '*')`)
+    const [,, manifestString] = await p
+    const manifest = JSON.parse(manifestString)
+
+    expect(manifest.name).to.equal(actualManifest.name)
+    expect(manifest.content_scripts.length).to.equal(actualManifest.content_scripts.length)
+  })
+})