chore: remove app.makeSingleInstance / releaseSingleInstance (#14518)

spec/api-app-spec.js

@@ -202,28 +202,6 @@ describe('app module', () => {
     })
   })
 
-  // TODO(MarshallOfSound) - Remove in 4.0.0
-  describe('app.makeSingleInstance', () => {
-    it('prevents the second launch of app', function (done) {
-      this.timeout(120000)
-      const appPath = path.join(__dirname, 'fixtures', 'api', 'singleton-old')
-      // First launch should exit with 0.
-      const first = ChildProcess.spawn(remote.process.execPath, [appPath])
-      first.once('exit', code => {
-        expect(code).to.equal(0)
-      })
-      // Start second app when received output.
-      first.stdout.once('data', () => {
-        // Second launch should exit with 1.
-        const second = ChildProcess.spawn(remote.process.execPath, [appPath])
-        second.once('exit', code => {
-          expect(code).to.equal(1)
-          done()
-        })
-      })
-    })
-  })
-
   describe('app.requestSingleInstanceLock', () => {
     it('prevents the second launch of app', function (done) {
       this.timeout(120000)

spec/fixtures/api/singleton-old/main.js

@@ -1,13 +0,0 @@
-const {app} = require('electron')
-
-app.once('ready', () => {
-  console.log('started')  // ping parent
-})
-
-const shouldExit = app.makeSingleInstance(() => {
-  setImmediate(() => app.exit(0))
-})
-
-if (shouldExit) {
-  app.exit(1)
-}

spec/fixtures/api/singleton-old/package.json

@@ -1,5 +0,0 @@
-{
-  "name": "electron-app-singleton",
-  "main": "main.js"
-}
-