Ensure libusb_close is called from the FILE thread.

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 <numeric>
 #include <utility>
 #include <vector>
@@ skipping 764 matching lines @@
     : device_(device),
       handle_(handle),
       context_(context),
       task_runner_(base::ThreadTaskRunnerHandle::Get()),
       blocking_task_runner_(blocking_task_runner) {
   DCHECK(handle) << "Cannot create device with NULL handle.";
 }
 
 UsbDeviceHandleImpl::~UsbDeviceHandleImpl() {
   // This class is RefCountedThreadSafe and so the destructor may be called on
-  // any thread.
-  libusb_close(handle_);
+  // any thread. libusb is not safe to reentrancy so be sure not to try to close
+  // the device from inside a transfer completion callback.
+  if (blocking_task_runner_->RunsTasksOnCurrentThread()) {
+    libusb_close(handle_);
+  } else {
+    blocking_task_runner_->PostTask(FROM_HERE,
+                                    base::Bind(&libusb_close, handle_));
+  }
 }
 
 void UsbDeviceHandleImpl::SetConfigurationOnBlockingThread(
     int configuration_value,
     const ResultCallback& callback) {
   int rv = libusb_set_configuration(handle_, configuration_value);
   if (rv != LIBUSB_SUCCESS) {
     USB_LOG(EVENT) << "Failed to set configuration " << configuration_value
                    << ": " << ConvertPlatformUsbErrorToString(rv);
   }
@@ skipping 323 matching lines @@
     map_entry.second = nullptr;
     blocking_task_runner_->ReleaseSoon(FROM_HERE, interface_claimer);
   }
 
   // Cannot close device handle here. Need to wait for libusb_cancel_transfer to
   // finish.
   device_ = nullptr;
 }
 
 }  // namespace device