ppapi: Cleanup class/struct forward declarations

ppapi/utility/websocket/websocket_api.h

 // Copyright (c) 2012 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 PPAPI_UTILITY_WEBSOCKET_WEBSOCKET_API_H_
 #define PPAPI_UTILITY_WEBSOCKET_WEBSOCKET_API_H_
 
 #include <stdint.h>
 
 #include "ppapi/c/ppb_websocket.h"
 
 /// @file
 /// This file defines the WebSocketAPI interface.
 
 namespace pp {
 
-class CompletionCallback;
 class Instance;
 class Var;
 
 /// The <code>WebSocketAPI</code> class
 class WebSocketAPI {
  public:
   /// Constructs a WebSocketAPI object.
   explicit WebSocketAPI(Instance* instance);
 
   /// Destructs a WebSocketAPI object.
@@ skipping 95 matching lines @@
   virtual void HandleWebSocketError() = 0;
 
  private:
   class Implement;
   Implement* impl_;
 };
 
 }  // namespace pp
 
 #endif  // PPAPI_UTILITY_WEBSOCKET_WEBSOCKET_API_H_