Move WebpDecoder from ios/web to components/image_fetcher

ios/web/public/image_fetcher/webp_decoder.h

-// Copyright 2013 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 IOS_WEB_PUBLIC_IMAGE_FETCHER_WEBP_DECODER_H_
-#define IOS_WEB_PUBLIC_IMAGE_FETCHER_WEBP_DECODER_H_
-
-#import <Foundation/Foundation.h>
-#include <stddef.h>
-
-#include <memory>
-
-#import "base/mac/scoped_nsobject.h"
-#include "base/memory/ref_counted.h"
-#include "third_party/libwebp/webp/decode.h"
-
-@class NSData;
-
-namespace webp_transcode {
-
-// Decodes a WebP image into either JPEG, PNG or uncompressed TIFF.
-class WebpDecoder : public base::RefCountedThreadSafe<WebpDecoder> {
- public:
-  // Format of the decoded image.
-  // This enum is used for UMA reporting, keep it in sync with the histogram
-  // definition.
-  enum DecodedImageFormat { JPEG = 1, PNG, TIFF, DECODED_FORMAT_COUNT };
-
-  class Delegate : public base::RefCountedThreadSafe<WebpDecoder::Delegate> {
-   public:
-    virtual void OnFinishedDecoding(bool success) = 0;
-    virtual void SetImageFeatures(size_t total_size,  // In bytes.
-                                  DecodedImageFormat format) = 0;
-    virtual void OnDataDecoded(NSData* data) = 0;
-
-   protected:
-    friend class base::RefCountedThreadSafe<WebpDecoder::Delegate>;
-    virtual ~Delegate() {}
-  };
-
-  explicit WebpDecoder(WebpDecoder::Delegate* delegate);
-
-  // Returns an NSData object containing the decoded image data of the given
-  // webp_image. Returns nil in case of failure.
-  static NSData* DecodeWebpImage(NSData* webp_image);
-
-  // Returns true if the given image_data is a WebP image.
-  //
-  // Every WebP file contains a 12 byte file header in the beginning of the
-  // file.
-  // A WebP file header starts with the four ASCII characters "RIFF". The next
-  // four bytes contain the image size and the last four header bytes contain
-  // the four ASCII characters "WEBP".
-  //
-  // WebP file header:
-  //                                  1 1
-  // Byte Nr.     0 1 2 3 4 5 6 7 8 9 0 1
-  // Byte value [ R I F F ? ? ? ? W E B P  ]
-  //
-  // For more information see:
-  // https://developers.google.com/speed/webp/docs/riff_container#webp_file_header
-  static bool IsWebpImage(const std::string& image_data);
-
-  // For tests.
-  static size_t GetHeaderSize();
-
-  // Main entry point.
-  void OnDataReceived(NSData* data);
-
-  // Stops the decoding.
-  void Stop();
-
- private:
-  struct WebPIDecoderDeleter {
-    inline void operator()(WebPIDecoder* ptr) const { WebPIDelete(ptr); }
-  };
-
-  enum State { READING_FEATURES, READING_DATA, DONE };
-
-  friend class base::RefCountedThreadSafe<WebpDecoder>;
-  virtual ~WebpDecoder();
-
-  // Implements WebP image decoding state machine steps.
-  void DoReadFeatures(NSData* data);
-  void DoReadData(NSData* data);
-  bool DoSendData();
-
-  scoped_refptr<WebpDecoder::Delegate> delegate_;
-  WebPDecoderConfig config_;
-  WebpDecoder::State state_;
-  std::unique_ptr<WebPIDecoder, WebPIDecoderDeleter> incremental_decoder_;
-  base::scoped_nsobject<NSData> output_buffer_;
-  base::scoped_nsobject<NSMutableData> features_;
-  int has_alpha_;
-};
-
-}  // namespace webp_transcode
-
-#endif  // IOS_WEB_PUBLIC_IMAGE_FETCHER_WEBP_DECODER_H_