device/usb/usb_service.h

   1 // Copyright 2014 The Chromium Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style license that can be
   3 // found in the LICENSE file.
   4
   5 #ifndef DEVICE_USB_USB_SERVICE_H_
   6 #define DEVICE_USB_USB_SERVICE_H_
   7
   8 #include <vector>
   9
  10 #include "base/memory/ref_counted.h"
  11 #include "base/memory/scoped_ptr.h"
  12 #include "base/observer_list.h"
  13 #include "base/threading/non_thread_safe.h"
  14
  15 namespace base {
  16 class SingleThreadTaskRunner;
  17 }
  18
  19 namespace device {
  20
  21 class UsbDevice;
  22
  23 // The USB service handles creating and managing an event handler thread that is
  24 // used to manage and dispatch USB events. It is also responsible for device
  25 // discovery on the system, which allows it to re-use device handles to prevent
  26 // competition for the same USB device.
  27 //
  28 // All functions on this object must be called from a thread with a
  29 // MessageLoopForIO (for example, BrowserThread::FILE).
  30 class UsbService : public base::NonThreadSafe {
  31  public:
  32   class Observer {
  33    public:
  34     // These events are delivered from the thread on which the UsbService object
  35     // was created.
  36     virtual void OnDeviceAdded(scoped_refptr<UsbDevice> device);
  37     virtual void OnDeviceRemoved(scoped_refptr<UsbDevice> device);
  38     // For observers that need to process device removal after others have run.
  39     // Should not depend on any other service's knowledge of connected devices.
  40     virtual void OnDeviceRemovedCleanup(scoped_refptr<UsbDevice> device);
  41   };
  42
  43   // The UI task runner reference is used to talk to the PermissionBrokerClient
  44   // on ChromeOS (UI thread). Returns NULL when initialization fails.
  45   static UsbService* GetInstance(
  46       scoped_refptr<base::SingleThreadTaskRunner> ui_task_runner);
  47
  48   static void SetInstanceForTest(UsbService* instance);
  49
  50   virtual scoped_refptr<UsbDevice> GetDeviceById(uint32 unique_id) = 0;
  51
  52   // Get all of the devices attached to the system, inserting them into
  53   // |devices|. Clears |devices| before use. The result will be sorted by id
  54   // in increasing order.
  55   virtual void GetDevices(std::vector<scoped_refptr<UsbDevice> >* devices) = 0;
  56
  57   void AddObserver(Observer* observer);
  58   void RemoveObserver(Observer* observer);
  59
  60  protected:
  61   UsbService();
  62   virtual ~UsbService();
  63
  64   void NotifyDeviceAdded(scoped_refptr<UsbDevice> device);
  65   void NotifyDeviceRemoved(scoped_refptr<UsbDevice> device);
  66
  67   ObserverList<Observer, true> observer_list_;
  68
  69  private:
  70   class Destroyer;
  71
  72   DISALLOW_COPY_AND_ASSIGN(UsbService);
  73 };
  74
  75 }  // namespace device
  76
  77 #endif  // DEVICE_USB_USB_SERVICE_H_