Move UsbService to its own component.

components/usb_service/usb_service.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_SERVICE_H_
-#define CHROME_BROWSER_USB_USB_SERVICE_H_
+#ifndef COMPONENTS_USB_SERVICE_USB_SERVICE_H_
+#define COMPONENTS_USB_SERVICE_USB_SERVICE_H_
 
 #include <map>
 #include <utility>
 #include <vector>
 
 #include "base/basictypes.h"
 #include "base/memory/ref_counted.h"
 #include "base/memory/scoped_ptr.h"
 #include "base/message_loop/message_loop.h"
 #include "base/threading/non_thread_safe.h"
+#include "components/usb_service/usb_service_export.h"
+
+struct libusb_device;
+struct libusb_context;
+
+namespace usb_service {
 
 typedef struct libusb_device* PlatformUsbDevice;
 typedef struct libusb_context* PlatformUsbContext;
 
 class UsbContext;
 class UsbDevice;
 
 // The USB service handles creating and managing an event handler thread that is
 // used to manage and dispatch USB events. It is also responsible for device
 // discovery on the system, which allows it to re-use device handles to prevent
 // competition for the same USB device.
-class UsbService : public base::MessageLoop::DestructionObserver,
-                   public base::NonThreadSafe {
+class USB_SERVICE_EXPORT UsbService
+    : public base::MessageLoop::DestructionObserver,
+      public base::NonThreadSafe {
  public:
   typedef scoped_ptr<std::vector<scoped_refptr<UsbDevice> > >
       ScopedDeviceVector;
 
   // Must be called on FILE thread.
   // Returns NULL when failed to initialized.
   static UsbService* GetInstance();
 
   scoped_refptr<UsbDevice> GetDeviceById(uint32 unique_id);
 
@@ skipping 19 matching lines @@
   // TODO(ikarienator): Figure out a better solution.
   uint32 next_unique_id_;
 
   // The map from PlatformUsbDevices to UsbDevices.
   typedef std::map<PlatformUsbDevice, scoped_refptr<UsbDevice> > DeviceMap;
   DeviceMap devices_;
 
   DISALLOW_COPY_AND_ASSIGN(UsbService);
 };
 
-#endif  // CHROME_BROWSER_USB_USB_SERVICE_H_
+}  // namespace usb_service
+
+#endif  // COMPONENTS_USB_SERVICE_USB_SERVICE_H_