Add chrome://usb-internals page for adding and removing test devices.

device/usb/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 DEVICE_USB_USB_SERVICE_H_
 #define DEVICE_USB_USB_SERVICE_H_
 
 #include <memory>
 #include <string>
 #include <unordered_map>
+#include <unordered_set>
 #include <vector>
 
 #include "base/bind_helpers.h"
 #include "base/macros.h"
 #include "base/memory/ref_counted.h"
 #include "base/observer_list.h"
 #include "base/threading/non_thread_safe.h"
 
 namespace base {
 class SequencedTaskRunner;
@@ skipping 36 matching lines @@
   virtual ~UsbService();
 
   scoped_refptr<UsbDevice> GetDevice(const std::string& guid);
 
   // Enumerates available devices.
   virtual void GetDevices(const GetDevicesCallback& callback);
 
   void AddObserver(Observer* observer);
   void RemoveObserver(Observer* observer);
 
+  // Methods to add and remove devices for testing purposes. Only a device added
+  // by this method can be removed by RemoveDeviceForTesting().
+  void AddDeviceForTesting(scoped_refptr<UsbDevice> device);
+  void RemoveDeviceForTesting(const std::string& device_guid);
+  void GetTestDevices(std::vector<scoped_refptr<UsbDevice>>* devices);
+
  protected:
   UsbService(scoped_refptr<base::SingleThreadTaskRunner> task_runner,
              scoped_refptr<base::SequencedTaskRunner> blocking_task_runner);
 
   void NotifyDeviceAdded(scoped_refptr<UsbDevice> device);
   void NotifyDeviceRemoved(scoped_refptr<UsbDevice> device);
 
   scoped_refptr<base::SingleThreadTaskRunner> task_runner() {
     return task_runner_;
   }
 
   scoped_refptr<base::SequencedTaskRunner> blocking_task_runner() {
     return blocking_task_runner_;
   }
 
   std::unordered_map<std::string, scoped_refptr<UsbDevice>>& devices() {
     return devices_;
   }
 
  private:
   friend void base::DeletePointer<UsbService>(UsbService* service);
 
   scoped_refptr<base::SingleThreadTaskRunner> task_runner_;
   scoped_refptr<base::SequencedTaskRunner> blocking_task_runner_;
   std::unordered_map<std::string, scoped_refptr<UsbDevice>> devices_;
+  std::unordered_set<std::string> testing_devices_;
   base::ObserverList<Observer, true> observer_list_;
 
   DISALLOW_COPY_AND_ASSIGN(UsbService);
 };
 
 }  // namespace device
 
 #endif  // DEVICE_USB_USB_SERVICE_H_