Add ios_image_decoder_impl.*

components/image_fetcher/image_decoder.h

 // Copyright 2016 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 COMPONENTS_IMAGE_FETCHER_IMAGE_DECODER_H_
 #define COMPONENTS_IMAGE_FETCHER_IMAGE_DECODER_H_
 
 #include <string>
+
 #include "base/callback_forward.h"
+#include "base/macros.h"
 
 namespace gfx {
 class Image;
 }  // namespace gfx
 
 namespace image_fetcher {
 
 using ImageDecodedCallback = base::Callback<void(const gfx::Image&)>;
 
 // ImageDecoder defines the common interface for decoding images.
 class ImageDecoder {
  public:
   ImageDecoder() {}
   virtual ~ImageDecoder() {}
 
   // Decodes the passed |image_data| and runs the given callback. The callback
   // is run even if decoding the image fails. In case an error occured during
   // decoding the image an empty image is passed to the callback.
   virtual void DecodeImage(const std::string& image_data,
                            const ImageDecodedCallback& callback) = 0;
 
  private:
   DISALLOW_COPY_AND_ASSIGN(ImageDecoder);
 };
 
 }  // namespace image_fetcher
 
 #endif  // COMPONENTS_IMAGE_FETCHER_IMAGE_DECODER_H_