extensions: Cleanup class/struct fwd declarations

extensions/browser/api/hid/hid_api.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 EXTENSIONS_BROWSER_API_HID_HID_API_H_
 #define EXTENSIONS_BROWSER_API_HID_HID_API_H_
 
 #include <stddef.h>
 
 #include <memory>
 #include <string>
 
 #include "base/macros.h"
 #include "base/memory/ref_counted.h"
 #include "extensions/browser/api/api_resource_manager.h"
 #include "extensions/browser/api/hid/hid_connection_resource.h"
 #include "extensions/browser/api/hid/hid_device_manager.h"
 #include "extensions/browser/extension_function.h"
 #include "extensions/common/api/hid.h"
 
 namespace device {
 class HidConnection;
 class HidDeviceInfo;
-class HidService;
 }  // namespace device
 
 namespace net {
 class IOBuffer;
 }  // namespace net
 
 namespace extensions {
 
 class DevicePermissionsPrompt;
 
@@ skipping 171 matching lines @@
   void OnFinished(bool success);
 
   std::unique_ptr<api::hid::SendFeatureReport::Params> parameters_;
 
   DISALLOW_COPY_AND_ASSIGN(HidSendFeatureReportFunction);
 };
 
 }  // namespace extensions
 
 #endif  // EXTENSIONS_BROWSER_API_HID_HID_API_H_