iwyu: Use callback_old.h where appropriate, part 1.

remoting/base/encoder.h

 // Copyright (c) 2010 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 REMOTING_BASE_ENCODER_H_
 #define REMOTING_BASE_ENCODER_H_
 
 #include "base/basictypes.h"
-#include "base/callback.h"
+#include "base/callback_old.h"
 #include "media/base/data_buffer.h"
 
 namespace media {
   class DataBuffer;
 }
 
 namespace remoting {
 
 class CaptureData;
 class VideoPacket;
@@ skipping 21 matching lines @@
   // When encoded data is available, partial or full |data_available_callback|
   // is called.
   virtual void Encode(scoped_refptr<CaptureData> capture_data,
                       bool key_frame,
                       DataAvailableCallback* data_available_callback) = 0;
 };
 
 }  // namespace remoting
 
 #endif  // REMOTING_BASE_ENCODER_H_