webusb: Reject the promise if the device is already open.

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 233 matching lines @@
 void DeviceImpl::GetDeviceInfo(const GetDeviceInfoCallback& callback) {
   callback.Run(DeviceInfo::From(*device_));
 }
 
 void DeviceImpl::GetConfiguration(const GetConfigurationCallback& callback) {
   const UsbConfigDescriptor* config = device_->GetActiveConfiguration();
   callback.Run(config ? config->configuration_value : 0);
 }
 
 void DeviceImpl::Open(const OpenCallback& callback) {
-  device_->Open(
-      base::Bind(&DeviceImpl::OnOpen, weak_factory_.GetWeakPtr(), callback));
+  if (device_handle_)
+    callback.Run(OpenDeviceError::ALREADY_OPEN);
+  else
+    device_->Open(
+        base::Bind(&DeviceImpl::OnOpen, weak_factory_.GetWeakPtr(), callback));
 }
 
 void DeviceImpl::Close(const CloseCallback& callback) {
   CloseHandle();
   callback.Run();
 }
 
 void DeviceImpl::SetConfiguration(uint8_t value,
                                   const SetConfigurationCallback& callback) {
   if (!device_handle_) {
@@ skipping 189 matching lines @@
     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)));
 }
 
 }  // namespace usb
 }  // namespace device