Move iOS image_fetcher::ImageDecoder to layered component

components/image_fetcher/ios/ios_image_decoder_impl.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_IOS_IMAGE_DECODER_IMPL_H_
+#define COMPONENTS_IMAGE_FETCHER_IOS_IMAGE_DECODER_IMPL_H_
+
+#include "base/memory/ref_counted.h"
+#include "components/image_fetcher/image_decoder.h"
+
+namespace base {
+class TaskRunner;
+}
+
+namespace image_fetcher {
+
+// Factory for iOS specific implementation of ImageDecoder.
+std::unique_ptr<ImageDecoder> CreateIOSImageDecoder(
+    scoped_refptr<base::TaskRunner> task_runner);
+
+}  // namespace image_fetcher
+
+#endif  // COMPONENTS_IMAGE_FETCHER_IOS_IMAGE_DECODER_IMPL_H_