Remove the old image fetcher

ios/chrome/browser/net/mock_image_fetcher.h

-// Copyright 2015 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_CHROME_BROWSER_NET_MOCK_IMAGE_FETCHER_H_
-#define IOS_CHROME_BROWSER_NET_MOCK_IMAGE_FETCHER_H_
-
-#import "ios/chrome/browser/net/image_fetcher.h"
-
-#include "testing/gmock/include/gmock/gmock.h"
-
-// Mock the ImageFetcher utility class, which can be used to asynchronously
-// retrieve an image from an URL.
-class MockImageFetcher : public ImageFetcher {
- public:
-  explicit MockImageFetcher(const scoped_refptr<base::TaskRunner>& task_runner);
-  ~MockImageFetcher() override;
-
-  MOCK_METHOD4(StartDownload,
-               void(const GURL& url,
-                    ImageFetchedCallback callback,
-                    const std::string& referrer,
-                    net::URLRequest::ReferrerPolicy referrer_policy));
-  MOCK_METHOD2(StartDownload,
-               void(const GURL& url, ImageFetchedCallback callback));
-  MOCK_METHOD1(SetRequestContextGetter,
-               void(const scoped_refptr<net::URLRequestContextGetter>&
-                        request_context_getter));
-};
-
-#endif  // IOS_CHROME_BROWSER_NET_MOCK_IMAGE_FETCHER_H_