feat: add support for WebUSB (#36289)

* feat: add support for WebUSB

* fixup for gn check

* fixup gn check on Windows

* Apply review feedback

Co-authored-by: Charles Kerr <charles@charleskerr.com>

* chore: address review feedback

* chore: removed unneeded code

* Migrate non-default ScopedObservation<> instantiations to ScopedObservationTraits<> in chrome/browser/

4016595

Co-authored-by: Charles Kerr <charles@charleskerr.com>

docs/fiddles/features/web-usb/main.js

@@ -0,0 +1,72 @@
+const {app, BrowserWindow} = require('electron')
+const e = require('express')
+const path = require('path')
+
+function createWindow () {
+  const mainWindow = new BrowserWindow({
+    width: 800,
+    height: 600
+  })
+  
+  let grantedDeviceThroughPermHandler
+
+  mainWindow.webContents.session.on('select-usb-device', (event, details, callback) => {
+    //Add events to handle devices being added or removed before the callback on
+    //`select-usb-device` is called.
+    mainWindow.webContents.session.on('usb-device-added', (event, device) => {    
+      console.log('usb-device-added FIRED WITH', device)
+      //Optionally update details.deviceList
+    })
+  
+    mainWindow.webContents.session.on('usb-device-removed', (event, device) => {
+      console.log('usb-device-removed FIRED WITH', device)
+      //Optionally update details.deviceList
+    })
+
+    event.preventDefault()
+    if (details.deviceList && details.deviceList.length > 0) {
+      const deviceToReturn  = details.deviceList.find((device) => {
+        if (!grantedDeviceThroughPermHandler || (device.deviceId != grantedDeviceThroughPermHandler.deviceId)) {
+          return true
+        }
+      })
+      if (deviceToReturn) {
+        callback(deviceToReturn.deviceId)        
+      } else {
+        callback()
+      }
+    }
+  })
+
+  mainWindow.webContents.session.setPermissionCheckHandler((webContents, permission, requestingOrigin, details) => {
+    if (permission === 'usb' && details.securityOrigin === 'file:///') {
+      return true
+    }
+  })
+
+  
+  mainWindow.webContents.session.setDevicePermissionHandler((details) => {
+    if (details.deviceType === 'usb' && details.origin === 'file://') {
+      if (!grantedDeviceThroughPermHandler) {        
+        grantedDeviceThroughPermHandler = details.device
+        return true
+      } else {
+        return false
+      }
+    }
+  })
+  
+  mainWindow.loadFile('index.html')
+}
+
+app.whenReady().then(() => {
+  createWindow()
+  
+  app.on('activate', function () {
+    if (BrowserWindow.getAllWindows().length === 0) createWindow()
+  })
+})
+
+app.on('window-all-closed', function () {
+  if (process.platform !== 'darwin') app.quit()
+})