Experimental USB API implementation.

chrome/browser/extensions/api/usb/usb_device_resource.h

+// Copyright (c) 2012 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 CHROME_BROWSER_EXTENSIONS_API_USB_USB_DEVICE_RESOURCE_H_
+#define CHROME_BROWSER_EXTENSIONS_API_USB_USB_DEVICE_RESOURCE_H_
+#pragma once
+
+#include <set>
+
+#include "base/basictypes.h"
+#include "base/memory/linked_ptr.h"
+#include "base/synchronization/lock.h"
+#include "chrome/browser/extensions/api/api_resource.h"
+#include "chrome/common/extensions/api/experimental.usb.h"
+
+class UsbDevice;
+
+namespace net {
+class IOBuffer;
+}  // namespace net
+
+namespace extensions {
+
+class APIResourceEventNotifier;
+
+// A UsbDeviceResource is an APIResource wrapper for a UsbDevice. When invoking
+// transfers on the underlying device it will use the APIResourceEventNotifier
+// associated with the underlying APIResource to deliver completion messages.
+class UsbDeviceResource : public APIResource {
+ public:
+  UsbDeviceResource(APIResourceEventNotifier *notifier, UsbDevice *device);
+  virtual ~UsbDeviceResource();
+
+  // All of the *Transfer variants that are exposed here adapt their arguments
+  // for the underlying UsbDevice's interface and invoke the corresponding
+  // methods with completion callbacks that call OnTransferComplete on the vent
+  // notifier.
+  void ControlTransfer(
+      const api::experimental_usb::ControlTransferInfo &transfer);
+  void InterruptTransfer(
+      const api::experimental_usb::GenericTransferInfo &transfer);
+  void BulkTransfer(const api::experimental_usb::GenericTransferInfo &transfer);
+
+ private:
+  // Invoked by the underlying device's transfer callbacks. Indicates transfer
+  // completion to the APIResource's event notifier.
+  void TransferComplete(net::IOBuffer *buffer, const size_t length,
+                        int success);
+
+  scoped_refptr<UsbDevice> device_;
+
+  // pending_transfers_ is used to track the number of transfers that are
+  // currently in flight. Access to pending_transfers_ is protected by lock_.
+  base::Lock lock_;
+   int pending_transfers_;
+
+  DISALLOW_EVIL_CONSTRUCTORS(UsbDeviceResource);
+};
+
+}  // namespace extensions
+
+#endif  // CHROME_BROWSER_EXTENSIONS_API_USB_USB_DEVICE_RESOURCE_H_