Fixes crashing in RequestUsbDevicesAccess

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

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "chrome/browser/extensions/api/usb/usb_api.h"
 
 #include <string>
 #include <vector>
 
 #include "base/memory/scoped_ptr.h"
@@ skipping 307 matching lines @@
   }
   (*i)->RequestUsbAcess(interface_id, base::Bind(RequestUsbDevicesAccessHelper,
                                                  base::Passed(devices.Pass()),
                                                  i, interface_id, callback));
 }
 
 void RequestUsbDevicesAccess(
     ScopedDeviceVector devices,
     int interface_id,
     const base::Callback<void(ScopedDeviceVector result)>& callback) {
+  if (devices->empty()) {
+    callback.Run(devices.Pass());
+    return;
+  }
   (*devices->begin())->RequestUsbAcess(
       interface_id,
       base::Bind(RequestUsbDevicesAccessHelper, base::Passed(devices.Pass()),
                  devices->begin(), interface_id, callback));
 }
 #endif  // OS_CHROMEOS
 
 base::DictionaryValue* CreateTransferInfo(
     UsbTransferStatus status,
     scoped_refptr<net::IOBuffer> data,
@@ skipping 819 matching lines @@
     SetResult(new base::FundamentalValue(false));
     CompleteWithError(kErrorResetDevice);
     return;
   }
 
   SetResult(new base::FundamentalValue(true));
   AsyncWorkCompleted();
 }
 
 }  // namespace extensions