Enable WebUSB device detection when using the new Windows USB backend.

chrome/browser/usb/web_usb_detector.cc

Index: chrome/browser/usb/web_usb_detector.cc
diff --git a/chrome/browser/usb/web_usb_detector.cc b/chrome/browser/usb/web_usb_detector.cc
index 8bf90ddead499be814047d2624da60a87a312d80..8069062408a9ba244145bf694bf0c8988a0785f9 100644
--- a/chrome/browser/usb/web_usb_detector.cc
+++ b/chrome/browser/usb/web_usb_detector.cc
@@ -6,6 +6,7 @@
 
 #include <utility>
 
+#include "base/feature_list.h"
 #include "base/macros.h"
 #include "base/metrics/histogram_macros.h"
 #include "base/strings/utf_string_conversions.h"
@@ -17,6 +18,7 @@
 #include "chrome/grit/theme_resources.h"
 #include "content/public/common/origin_util.h"
 #include "device/base/device_client.h"
+#include "device/base/features.h"
 #include "device/usb/usb_device.h"
 #include "device/usb/usb_ids.h"
 #include "ui/base/l10n/l10n_util.h"
@@ -118,9 +120,14 @@ WebUsbDetector::WebUsbDetector() : observer_(this) {}
 WebUsbDetector::~WebUsbDetector() {}
 
 void WebUsbDetector::Initialize() {
-// Disabled on Windows due to jank and hangs caused by enumerating devices.
-// https://crbug.com/656702
-#if !defined(OS_WIN)
+#if defined(OS_WIN)
+  // The WebUSB device detector is disabled on Windows due to jank and hangs
+  // caused by enumerating devices. The new USB backend is designed to resolve
+  // these issues so enable it for testing. https://crbug.com/656702
+  if (!base::FeatureList::IsEnabled(device::kNewUsbBackend))
+    return;
+#endif  // defined(OS_WIN)
+
   SCOPED_UMA_HISTOGRAM_TIMER("WebUsb.DetectorInitialization");
   device::UsbService* usb_service =
       device::DeviceClient::Get()->GetUsbService();
@@ -128,7 +135,6 @@ void WebUsbDetector::Initialize() {
     return;
 
   observer_.Add(usb_service);
-#endif
 }
 
 void WebUsbDetector::OnDeviceAdded(scoped_refptr<device::UsbDevice> device) {