Ensure tests don't depend on fake devices being added synchronously

third_party/WebKit/LayoutTests/usb/usbDevice-iframe.html

Index: third_party/WebKit/LayoutTests/usb/usbDevice-iframe.html
diff --git a/third_party/WebKit/LayoutTests/usb/usbDevice-iframe.html b/third_party/WebKit/LayoutTests/usb/usbDevice-iframe.html
index b63743da10699cf677932f9f6b718a476223db38..b6514072106d3b1b10da023a877cb1fe70a3c2ac 100644
--- a/third_party/WebKit/LayoutTests/usb/usbDevice-iframe.html
+++ b/third_party/WebKit/LayoutTests/usb/usbDevice-iframe.html
@@ -11,7 +11,7 @@ function runIframeDisconnectTest(onDeviceConnected) {
   return navigator.usb.test.initialize().then(() => {
     return new Promise((resolve, reject) => {
       let opened = false;
-      let fakeDeviceGuid = null;
+      let fakeDevice = null;
 
       let iframe = document.createElement('iframe');
       iframe.src = 'resources/open-in-iframe.html';
@@ -23,7 +23,7 @@ function runIframeDisconnectTest(onDeviceConnected) {
 
       window.onmessage = messageEvent => {
         if (messageEvent.data == 'Ready') {
-          fakeDeviceGuid = navigator.usb.test.addFakeDevice(fakeDeviceInit);
+          fakeDevice = navigator.usb.test.addFakeDevice(fakeDeviceInit);
         } else if (messageEvent.data == 'Success') {
           opened = true;
           onDeviceConnected(iframe);
@@ -32,8 +32,8 @@ function runIframeDisconnectTest(onDeviceConnected) {
         }
       };
 
-      navigator.usb.test.ondeviceclose = guid => {
-        assert_equals(guid, fakeDeviceGuid);
+      navigator.usb.test.ondeviceclose = closedFakeDevice => {
+        assert_equals(closedFakeDevice, fakeDevice);
         assert_true(opened);
         resolve();
       };