UsbDeviceHandleImpl must hold a scoped_refptr to UsbDeviceImpl.

device/usb/usb_device_handle_impl.cc

 // Copyright 2014 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 "device/usb/usb_device_handle_impl.h"
 
 #include <algorithm>
 #include <vector>
 
 #include "base/bind.h"
@@ skipping 459 matching lines @@
   // Because device_handle_ is a weak pointer it is guaranteed that the callback
   // will be discarded if the handle has been freed.
   Transfer* tmp_transfer = transfer.get();  // base::Passed invalidates transfer
   tmp_transfer->task_runner_->PostTask(
       FROM_HERE, base::Bind(&UsbDeviceHandleImpl::CompleteTransfer,
                             tmp_transfer->device_handle_,
                             base::Passed(&transfer)));
 }
 
 UsbDeviceHandleImpl::UsbDeviceHandleImpl(scoped_refptr<UsbContext> context,
-                                         UsbDeviceImpl* device,
+                                         scoped_refptr<UsbDeviceImpl> device,
                                          PlatformUsbDeviceHandle handle)
     : device_(device),
       handle_(handle),
       context_(context),
       task_runner_(base::ThreadTaskRunnerHandle::Get()),
       weak_factory_(this) {
   DCHECK(handle) << "Cannot create device with NULL handle.";
 }
 
 UsbDeviceHandleImpl::~UsbDeviceHandleImpl() {
   DCHECK(thread_checker_.CalledOnValidThread());
 
   libusb_close(handle_);
   handle_ = NULL;
 }
 
 scoped_refptr<UsbDevice> UsbDeviceHandleImpl::GetDevice() const {
-  return static_cast<UsbDevice*>(device_);
+  return device_;
 }
 
 void UsbDeviceHandleImpl::Close() {
   DCHECK(thread_checker_.CalledOnValidThread());
   if (device_)
     device_->Close(this);
 }
 
 bool UsbDeviceHandleImpl::SetConfiguration(int configuration_value) {
   DCHECK(thread_checker_.CalledOnValidThread());
@@ skipping 347 matching lines @@
   // Attempt-release all the interfaces.
   // It will be retained until the transfer cancellation is finished.
   claimed_interfaces_.clear();
 
   // Cannot close device handle here. Need to wait for libusb_cancel_transfer to
   // finish.
   device_ = NULL;
 }
 
 }  // namespace device