Fixes leaking transfer objects due to improper USB handle closure.

chrome/browser/extensions/api/usb/usb_api.cc

Index: chrome/browser/extensions/api/usb/usb_api.cc
diff --git a/chrome/browser/extensions/api/usb/usb_api.cc b/chrome/browser/extensions/api/usb/usb_api.cc
index f21e1b8a58a6dd0030a1dfa518882b3f1c25717c..878e3625dd45655fd6e019ddaa846e11110f5c23 100644
--- a/chrome/browser/extensions/api/usb/usb_api.cc
+++ b/chrome/browser/extensions/api/usb/usb_api.cc
@@ -474,8 +474,12 @@ void UsbFindDevicesFunction::EnumerateDevices(
 
 void UsbFindDevicesFunction::OnEnumerationCompleted(
     ScopedDeviceVector devices) {
-  for (size_t i = 0; i < devices->size(); ++i)
-    device_handles_.push_back(devices->at(i)->Open());
+  for (size_t i = 0; i < devices->size(); ++i) {
+    scoped_refptr<UsbDeviceHandle> device_handle =
+      devices->at(i)->Open();
+    if (device_handle)
+      device_handles_.push_back(device_handle);
+  }
 
   BrowserThread::PostTask(
       BrowserThread::IO,