Destroy DeviceImpl when the underlying UsbDevice is disconnected.

device/usb/mojo/device_impl.cc

 // Copyright 2015 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/mojo/device_impl.h"
 
 #include <stddef.h>
 
 #include <algorithm>
 #include <numeric>
@@ skipping 161 matching lines @@
     scoped_refptr<net::IOBuffer> buffer,
     const std::vector<UsbDeviceHandle::IsochronousPacket>& packets) {
   callback->Run(mojo::Array<IsochronousPacketPtr>::From(packets));
 }
 
 }  // namespace
 
 DeviceImpl::DeviceImpl(scoped_refptr<UsbDevice> device,
                        PermissionProviderPtr permission_provider,
                        mojo::InterfaceRequest<Device> request)
-    : binding_(this, std::move(request)),
-      device_(device),
+    : device_(device),
+      observer_(this),
       permission_provider_(std::move(permission_provider)),
+      binding_(this, std::move(request)),
       weak_factory_(this) {
-  // This object owns itself and will be destroyed if either the message pipe
-  // it is bound to is closed or the PermissionProvider it depends on is
-  // unavailable.
+  DCHECK(device_);
+  // This object owns itself and will be destroyed if,
+  //  * the device is disconnected,
+  //  * the message pipe it is bound to is closed, or
+  //  * the PermissionProvider it depends on is unavailable.
+  observer_.Add(device_.get());
   binding_.set_connection_error_handler([this]() { delete this; });
   permission_provider_.set_connection_error_handler([this]() { delete this; });
 }
 
 DeviceImpl::~DeviceImpl() {
   CloseHandle();
 }
 
 void DeviceImpl::CloseHandle() {
   if (device_handle_)
@@ skipping 257 matching lines @@
   scoped_refptr<net::IOBuffer> buffer = CreateTransferBuffer(data.size());
   {
     const std::vector<uint8_t>& storage = data.storage();
     std::copy(storage.begin(), storage.end(), buffer->data());
   }
   device_handle_->IsochronousTransferOut(
       endpoint_address, buffer, packet_lengths.storage(), timeout,
       base::Bind(&OnIsochronousTransferOut, base::Passed(&callback_ptr)));
 }
 
+void DeviceImpl::OnDeviceRemoved(scoped_refptr<UsbDevice> device) {
+  DCHECK_EQ(device_, device);
+  delete this;
+}
+
 }  // namespace usb
 }  // namespace device