Adding UsbService and UsbDevice constructs.

chrome/browser/usb/usb_device.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_USB_USB_DEVICE_H_
+#define CHROME_BROWSER_USB_USB_DEVICE_H_
+#pragma once
+
+#include <map>
+
+#include "base/memory/ref_counted.h"
+#include "base/synchronization/lock.h"
+#include "net/base/completion_callback.h"
+#include "net/base/io_buffer.h"
+#include "third_party/libusb/libusb/libusb.h"
+
+typedef libusb_device *PlatformUsbDevice;
+typedef libusb_device_handle *PlatformUsbDeviceHandle;
+typedef libusb_transfer *PlatformUsbTransferHandle;

[miket_OOO, 2012/04/25 21:24:36]

style: whitespace should be after *.

[Garret Kelly, 2012/04/26 02:21:42]

Done.

+
+class UsbService;
+
+namespace net {
+class IOBuffer;
+}  // namespace net
+
+// A UsbDevice wraps the platform's underlying representation of what a USB
+// device actually is, and provides accessors for performing many of the
+// standard USB operations.
+class UsbDevice : public base::RefCounted<UsbDevice> {
+ public:
+  enum TransferDirection { IN, OUT };
+  enum TransferRequestType { STANDARD, CLASS, VENDOR, RESERVED };
+  enum TransferRecipient { DEVICE, INTERFACE, ENDPOINT, OTHER };
+
+  // Usually you will not want to directly create a UsbDevice, favouring to let

[miket_OOO, 2012/04/25 21:24:36]

"favouring": I'll let this spelling slide in light of your provenance.

[Garret Kelly, 2012/04/26 02:21:42]

gdk@determinist:~/sandbox/chrome/src$ git grep colour | wc -l
122
gdk@determinist:~/sandbox/chrome/src$ git grep color | wc -l
17708

Changed to en_US locale. :)

+  // the UsbService take care of the logistics of getting a platform device
+  // handle and handling events for it.
+  UsbDevice(UsbService *service, PlatformUsbDeviceHandle handle);
+
+  PlatformUsbDeviceHandle handle() { return handle_; }
+
+  // Close the USB device and release the underlying platform device.
+  void Close();
+
+  void ControlTransfer(const TransferDirection direction,
+                       const TransferRequestType request_type,
+                       const TransferRecipient recipient,
+                       const uint8 request,
+                       const uint16 value,
+                       const uint16 index,
+                       net::IOBuffer *buffer,

[miket_OOO, 2012/04/25 21:24:36]

Pointer placement (et seq.)

[Garret Kelly, 2012/04/26 02:21:42]

Done.

+                       const size_t length,
+                       const unsigned int timeout,
+                       const net::CompletionCallback &callback);
+
+  void BulkTransfer(const TransferDirection direction,
+                    const uint8 endpoint,
+                    net::IOBuffer *buffer,
+                    const size_t length,
+                    const unsigned int timeout,
+                    const net::CompletionCallback &callback);
+
+  void InterruptTransfer(const TransferDirection direction,
+                         const uint8 endpoint,
+                         net::IOBuffer *buffer,
+                         const size_t length,
+                         const unsigned int timeout,
+                         const net::CompletionCallback &callback);
+
+  // Normal code should not call this function. It is called by the platform's
+  // callback mechanism in such a way that it cannot be made private. Invokes
+  // the callbacks associated with a given transfer, and removes it from the
+  // in-flight transfer set.
+  void TransferComplete(PlatformUsbTransferHandle transfer);
+
+ private:
+  struct Transfer {
+    scoped_refptr<net::IOBuffer> buffer;
+    net::CompletionCallback callback;
+  };
+
+  friend class base::RefCounted<UsbDevice>;
+  virtual ~UsbDevice();
+
+  // Checks that the device has not yet been closed.
+  void CheckDevice();
+
+  // Starts tracking the USB transfer associated with a platform transfer
+  // handle. Retains the buffer and copies the completion callback until the
+  // transfer finishes, whereupon it invokes the callback then releases the
+  // buffer.
+  void AddTransfer(PlatformUsbTransferHandle handle, net::IOBuffer *buffer,
+                   const net::CompletionCallback &callback);
+
+  UsbService *const service_;

[miket_OOO, 2012/04/25 21:24:36]

It's nice to leave a comment explaining why a naked pointer can't be protected
with a RAII device.

[Garret Kelly, 2012/04/26 02:21:42]

Done.

+  PlatformUsbDeviceHandle handle_;
+
+  // transfers_ tracks all in-flight transfers associated with this device,
+  // allowing the device to retain the buffer and callback associated with a
+  // transfer until such time that it completes. It is protected by lock_.
+  base::Lock lock_;
+  std::map<PlatformUsbTransferHandle, Transfer> transfers_;
+
+  DISALLOW_EVIL_CONSTRUCTORS(UsbDevice);
+};
+
+#endif  // CHROME_BROWSER_USB_USB_DEVICE_H_