Move common ImageFetcher component files to core/

components/image_fetcher/request_metadata.cc

-// Copyright 2017 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 "components/image_fetcher/request_metadata.h"
-
-namespace image_fetcher {
-
-RequestMetadata::RequestMetadata()
-    : http_response_code(RESPONSE_CODE_INVALID), from_http_cache(false) {}
-
-bool operator==(const RequestMetadata& lhs, const RequestMetadata& rhs) {
-  return lhs.mime_type == rhs.mime_type &&
-         lhs.http_response_code == rhs.http_response_code &&
-         lhs.from_http_cache == rhs.from_http_cache;
-}
-
-bool operator!=(const RequestMetadata& lhs, const RequestMetadata& rhs) {
-  return !(lhs == rhs);
-}
-
-}  // namespace image_fetcher