Add API tests for the chrome.hid API.

device/hid/hid_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_HID_HID_SERVICE_H_
 #define DEVICE_HID_HID_SERVICE_H_
 
 #include <map>
 #include <string>
 #include <vector>
 
 #include "base/memory/ref_counted.h"
 #include "base/single_thread_task_runner.h"
 #include "base/threading/thread_checker.h"
 #include "device/hid/hid_device_info.h"
 
 namespace device {
 
 class HidConnection;
 
 class HidService {
  public:
   typedef base::Callback<void(scoped_refptr<HidConnection> connection)>
       ConnectCallback;
 
   static HidService* GetInstance(
       scoped_refptr<base::SingleThreadTaskRunner> file_task_runner,
       scoped_refptr<base::SingleThreadTaskRunner> ui_task_runner);
 
+  static void SetInstanceForTest(HidService* instance);
+
   // Enumerates and returns a list of device identifiers.
   virtual void GetDevices(std::vector<HidDeviceInfo>* devices);
 
   // Fills in a DeviceInfo struct with info for the given device_id.
   // Returns |true| if successful or |false| if |device_id| is invalid.
   bool GetDeviceInfo(const HidDeviceId& device_id, HidDeviceInfo* info) const;
 
   // Opens a connection to a device. The callback will be run with null on
   // failure.
   virtual void Connect(const HidDeviceId& device_id,
@@ skipping 18 matching lines @@
   class Destroyer;
 
   DeviceMap devices_;
 
   DISALLOW_COPY_AND_ASSIGN(HidService);
 };
 
 }  // namespace device
 
 #endif  // DEVICE_HID_HID_SERVICE_H_