Migrate WebUSB LayoutTests into external/wpt

third_party/WebKit/LayoutTests/external/wpt/webusb/resources/usb-helpers.js

 'use strict';
 
 function usb_test(func, name, properties) {
   promise_test(() => {
     return navigator.usb.test.initialize().then(() => {
       let testResult = func();
       let cleanup = () => {
         navigator.usb.test.reset();
       };
       testResult.then(cleanup, cleanup);
@@ skipping 56 matching lines @@
     } else if (Array.isArray(deviceInit[property])) {
       assert_equals(usbDevice[property].length, deviceInit[property].length);
       for (var i = 0; i < usbDevice[property].length; ++i)
         assertDeviceInfoEquals(usbDevice[property][i], deviceInit[property][i]);
     } else {
       assert_equals(usbDevice[property], deviceInit[property], property);
     }
   }
 }
 
-// TODO(reillyg): Remove when jyasskin upstreams this to testharness.js:
-// https://crbug.com/509058.
-function callWithKeyDown(functionCalledOnKeyPress) {
+function callWithTrustedClick(callback) {
   return new Promise(resolve => {
-    function onKeyPress() {
-      document.removeEventListener('keypress', onKeyPress, false);
-      resolve(functionCalledOnKeyPress());
-    }
-    document.addEventListener('keypress', onKeyPress, false);
-
-    eventSender.keyDown(' ', []);
+    let button = document.createElement('button');
+    button.textContent = 'click to continue test';
+    button.style.display = 'block';
+    button.style.fontSize = '20px';
+    button.style.padding = '10px';
+    button.onclick = () => {
+      resolve(callback());
+      document.body.removeChild(button);
+    };
+    document.body.appendChild(button);
   });
 }
-
-function runGarbageCollection() {
-  // Run gc() as a promise.
-  return new Promise((resolve, reject) => {
-    GCController.collect();
-    setTimeout(resolve, 0);
-  });
-}