Extracted UsbService as interface.

components/usb_service/usb_service.h

 // Copyright 2014 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 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 USB_SERVICE_EXPORT UsbService
-    : public base::MessageLoop::DestructionObserver,
-      public base::NonThreadSafe {
+class USB_SERVICE_EXPORT UsbService : protected base::NonThreadSafe {

[pfeldman, 2014/04/25 15:23:41]

Why protected?

  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);
+  static void SetInstanceForTest(UsbService* instance);
+
+  virtual scoped_refptr<UsbDevice> GetDeviceById(uint32 unique_id) = 0;
 
   // Get all of the devices attached to the system, inserting them into
   // |devices|. Clears |devices| before use. The result will be sorted by id
   // in increasing order. Must be called on FILE thread.
-  void GetDevices(std::vector<scoped_refptr<UsbDevice> >* devices);
+  virtual void GetDevices(std::vector<scoped_refptr<UsbDevice> >* devices) = 0;
 
-  // base::MessageLoop::DestructionObserver implementation.
-  virtual void WillDestroyCurrentMessageLoop() OVERRIDE;
-
- private:
+ protected:
   friend struct base::DefaultDeleter<UsbService>;
-
-  explicit UsbService(PlatformUsbContext context);
-  virtual ~UsbService();
-
-  // Enumerate USB devices from OS and Update devices_ map.
-  void RefreshDevices();
-
-  scoped_refptr<UsbContext> context_;
-
-  // 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_;
-
+  UsbService() {}
+  virtual ~UsbService() {}
   DISALLOW_COPY_AND_ASSIGN(UsbService);
 };
 
 }  // namespace usb_service
 
 #endif  // COMPONENTS_USB_SERVICE_USB_SERVICE_H_