UsbDeviceHandleImpl must hold a scoped_refptr to UsbDeviceImpl.

device/usb/usb_device_handle_impl.h

 // 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.
 
 #ifndef DEVICE_USB_USB_DEVICE_HANDLE_IMPL_H_
 #define DEVICE_USB_USB_DEVICE_HANDLE_IMPL_H_
 
 #include <map>
 #include <set>
 #include <vector>
@@ skipping 68 matching lines @@
                            unsigned int timeout,
                            const UsbTransferCallback& callback) override;
 
   PlatformUsbDeviceHandle handle() const { return handle_; }
 
  protected:
   friend class UsbDeviceImpl;
 
   // This constructor is called by UsbDevice.
   UsbDeviceHandleImpl(scoped_refptr<UsbContext> context,
-                      UsbDeviceImpl* device,
+                      scoped_refptr<UsbDeviceImpl> device,
                       PlatformUsbDeviceHandle handle);
 
   ~UsbDeviceHandleImpl() override;
 
  private:
   friend class Transfer;
 
   class InterfaceClaimer;
   class Transfer;
 
@@ skipping 19 matching lines @@
 
   // Invokes the callbacks associated with a given transfer, and removes it from
   // the in-flight transfer set.
   void CompleteTransfer(scoped_ptr<Transfer> transfer);
 
   bool GetSupportedLanguages();
 
   // Informs the object to drop internal references.
   void InternalClose();
 
-  UsbDeviceImpl* device_;
+  scoped_refptr<UsbDeviceImpl> device_;
 
   PlatformUsbDeviceHandle handle_;
 
   std::vector<uint16> languages_;
   std::map<uint8, base::string16> strings_;
 
   typedef std::map<int, scoped_refptr<InterfaceClaimer>> ClaimedInterfaceMap;
   ClaimedInterfaceMap claimed_interfaces_;
 
   // This set holds weak pointers to pending transfers.
@@ skipping 11 matching lines @@
 
   base::ThreadChecker thread_checker_;
   base::WeakPtrFactory<UsbDeviceHandleImpl> weak_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(UsbDeviceHandleImpl);
 };
 
 }  // namespace device
 
 #endif  // DEVICE_USB_USB_DEVICE_HANDLE_IMPL_H_