Move iOS image_fetcher::ImageDecoder to layered component

ios/chrome/browser/suggestions/ios_image_decoder_impl.mm

-// 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.
-
-#include "ios/chrome/browser/suggestions/ios_image_decoder_impl.h"
-
-#import <UIKit/UIKit.h>
-
-#include "base/callback.h"
-#import "base/mac/bind_objc_block.h"
-#include "base/macros.h"
-#include "base/memory/ptr_util.h"
-#include "base/memory/weak_ptr.h"
-#import "components/image_fetcher/ios/webp_decoder.h"
-#include "ios/web/public/web_thread.h"
-#include "ui/gfx/geometry/size.h"
-#include "ui/gfx/image/image.h"
-
-#if !defined(__has_feature) || !__has_feature(objc_arc)
-#error "This file requires ARC support."
-#endif
-
-namespace suggestions {
-
-class IOSImageDecoderImpl : public image_fetcher::ImageDecoder {
- public:
-  explicit IOSImageDecoderImpl(scoped_refptr<base::TaskRunner> task_runner);
-  ~IOSImageDecoderImpl() override;
-
-  // Note, that |desired_image_frame_size| is not supported
-  // (http://crbug/697596).
-  void DecodeImage(
-      const std::string& image_data,
-      const gfx::Size& desired_image_frame_size,
-      const image_fetcher::ImageDecodedCallback& callback) override;
-
- private:
-  void CreateUIImageAndRunCallback(
-      const image_fetcher::ImageDecodedCallback& callback,
-      NSData* image_data);
-
-  // The task runner used to decode images if necessary.
-  const scoped_refptr<base::TaskRunner> task_runner_;
-
-  // The WeakPtrFactory is used to cancel callbacks if ImageFetcher is
-  // destroyed during WebP decoding.
-  base::WeakPtrFactory<IOSImageDecoderImpl> weak_factory_;
-
-  DISALLOW_COPY_AND_ASSIGN(IOSImageDecoderImpl);
-};
-
-IOSImageDecoderImpl::IOSImageDecoderImpl(
-    scoped_refptr<base::TaskRunner> task_runner)
-    : task_runner_(std::move(task_runner)), weak_factory_(this) {
-  DCHECK(task_runner_.get());
-}
-
-IOSImageDecoderImpl::~IOSImageDecoderImpl() {}
-
-void IOSImageDecoderImpl::DecodeImage(
-    const std::string& image_data,
-    const gfx::Size& desired_image_frame_size,
-    const image_fetcher::ImageDecodedCallback& callback) {
-  // Convert the |image_data| std::string to an NSData buffer.
-  // The data is copied as it may have to outlive the caller in
-  // PostTaskAndReplyWithResult.
-  NSData* data =
-      [NSData dataWithBytes:image_data.data() length:image_data.size()];
-
-  // The WebP image format is not supported by iOS natively. Therefore WebP
-  // images need to be decoded explicitly,
-  if (webp_transcode::WebpDecoder::IsWebpImage(image_data)) {
-    base::PostTaskAndReplyWithResult(
-        task_runner_.get(), FROM_HERE, base::BindBlockArc(^NSData*() {
-          return webp_transcode::WebpDecoder::DecodeWebpImage(data);
-        }),
-        base::Bind(&IOSImageDecoderImpl::CreateUIImageAndRunCallback,
-                   weak_factory_.GetWeakPtr(), callback));
-  } else {
-    CreateUIImageAndRunCallback(callback, data);
-  }
-}
-
-void IOSImageDecoderImpl::CreateUIImageAndRunCallback(
-    const image_fetcher::ImageDecodedCallback& callback,
-    NSData* image_data) {
-  // Decode the image data using UIImage.
-  if (image_data) {
-    // "Most likely" always returns 1x images.
-    UIImage* ui_image = [UIImage imageWithData:image_data scale:1];
-    if (ui_image) {
-      // This constructor does not retain the image, but expects to take the
-      // ownership, therefore, |ui_image| is retained here, but not released
-      // afterwards.
-      gfx::Image gfx_image(ui_image, base::scoped_policy::RETAIN);
-      callback.Run(gfx_image);
-      return;
-    }
-  }
-  gfx::Image empty_image;
-  callback.Run(empty_image);
-}
-
-std::unique_ptr<image_fetcher::ImageDecoder> CreateIOSImageDecoder(
-    scoped_refptr<base::TaskRunner> task_runner) {
-  return base::MakeUnique<IOSImageDecoderImpl>(std::move(task_runner));
-}
-
-}  // namespace suggestions