refactor: printing implementation (#15143)

* refactor: basic printing

* move build files to chromium_src/BUILD.gn
* remove dependency on chrome prerender sources

* spec: move printing specs behind feature flag

* build: register pdf compositor service

spec/api-web-contents-spec.js

@@ -10,6 +10,7 @@ const { emittedOnce } = require('./events-helpers')
 const chai = require('chai')
 const dirtyChai = require('dirty-chai')
 
+const features = process.atomBinding('features')
 const { ipcRenderer, remote, clipboard } = require('electron')
 const { BrowserWindow, webContents, ipcMain, session } = remote
 const { expect } = chai
@@ -943,4 +944,61 @@ describe('webContents module', () => {
       done()
     })
   })
+
+  describe('getPrinterList()', () => {
+    before(function () {
+      if (!features.isPrintingEnabled()) {
+        return closeWindow(w).then(() => {
+          w = null
+          this.skip()
+        })
+      }
+    })
+
+    it('can get printer list', (done) => {
+      w.destroy()
+      w = new BrowserWindow({
+        show: false,
+        webPreferences: {
+          sandbox: true
+        }
+      })
+      w.loadURL('data:text/html,%3Ch1%3EHello%2C%20World!%3C%2Fh1%3E')
+      w.webContents.once('did-finish-load', () => {
+        const printers = w.webContents.getPrinters()
+        assert.strictEqual(Array.isArray(printers), true)
+        done()
+      })
+    })
+  })
+
+  describe('printToPDF()', () => {
+    before(function () {
+      if (!features.isPrintingEnabled()) {
+        return closeWindow(w).then(() => {
+          w = null
+          this.skip()
+        })
+      }
+    })
+
+    it('can print to PDF', (done) => {
+      w.destroy()
+      w = new BrowserWindow({
+        show: false,
+        webPreferences: {
+          sandbox: true
+        }
+      })
+      w.loadURL('data:text/html,%3Ch1%3EHello%2C%20World!%3C%2Fh1%3E')
+      w.webContents.once('did-finish-load', () => {
+        w.webContents.printToPDF({}, function (error, data) {
+          assert.strictEqual(error, null)
+          assert.strictEqual(data instanceof Buffer, true)
+          assert.notStrictEqual(data.length, 0)
+          done()
+        })
+      })
+    })
+  })
 })