Clean up HID backend and API.

device/hid/hid_service_win.h

Index: device/hid/hid_service_win.h
diff --git a/device/hid/hid_service_win.h b/device/hid/hid_service_win.h
index 428420ed9b0f41e8912afca83166f2b55d782b8e..9433799a9cd84913a67b297bbf8c81716ea1a324 100644
--- a/device/hid/hid_service_win.h
+++ b/device/hid/hid_service_win.h
@@ -1,23 +1,15 @@
-// Copyright (c) 2014 The Chromium Authors. All rights reserved.
+// 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_WIN_H_
 #define DEVICE_HID_HID_SERVICE_WIN_H_
 
-#include <map>
-#include <string>
-#include <vector>
-
-#include "base/basictypes.h"
-#include "base/memory/ref_counted.h"
-#include "device/hid/hid_device_info.h"
 #include "device/hid/hid_service.h"
 
 namespace device {
 
 class HidConnection;
-class HidService;
 
 class HidServiceWin : public HidService {
  public:
@@ -25,14 +17,15 @@ class HidServiceWin : public HidService {
 
   virtual void GetDevices(std::vector<HidDeviceInfo>* devices) OVERRIDE;
 
-  virtual scoped_refptr<HidConnection> Connect(std::string device_id) OVERRIDE;
+  virtual scoped_refptr<HidConnection> Connect(const std::string& device_id)
+      OVERRIDE;
 
  private:
   virtual ~HidServiceWin();
 
-  bool Enumerate();
-  void PlatformAddDevice(std::string device_path);
-  void PlatformRemoveDevice(std::string device_path);
+  void Enumerate();
+  void PlatformAddDevice(const std::string& device_path);
+  void PlatformRemoveDevice(const std::string& device_path);
 
   DISALLOW_COPY_AND_ASSIGN(HidServiceWin);
 };