extensions: Cleanup class/struct fwd declarations

extensions/browser/api/bluetooth/bluetooth_private_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_BLUETOOTH_BLUETOOTH_PRIVATE_API_H_
 #define EXTENSIONS_BROWSER_API_BLUETOOTH_BLUETOOTH_PRIVATE_API_H_
 
 #include "base/callback_forward.h"
 #include "base/macros.h"
 #include "device/bluetooth/bluetooth_device.h"
 #include "extensions/browser/api/bluetooth/bluetooth_extension_function.h"
 #include "extensions/browser/browser_context_keyed_api_factory.h"
 #include "extensions/browser/event_router.h"
 
 namespace device {
 class BluetoothAdapter;
 }
 
 namespace extensions {
 
-class BluetoothApiPairingDelegate;
-
 // The profile-keyed service that manages the bluetoothPrivate extension API.
 class BluetoothPrivateAPI : public BrowserContextKeyedAPI,
                             public EventRouter::Observer {
  public:
   static BrowserContextKeyedAPIFactory<BluetoothPrivateAPI>*
       GetFactoryInstance();
 
   explicit BluetoothPrivateAPI(content::BrowserContext* context);
   ~BluetoothPrivateAPI() override;
 
@@ skipping 152 matching lines @@
   void OnErrorCallback(device::BluetoothDevice::ConnectErrorCode error);
 
   DISALLOW_COPY_AND_ASSIGN(BluetoothPrivatePairFunction);
 };
 
 }  // namespace api
 
 }  // namespace extensions
 
 #endif  // EXTENSIONS_BROWSER_API_BLUETOOTH_BLUETOOTH_PRIVATE_API_H_