Remove the old image fetcher

ios/chrome/browser/net/mock_image_fetcher.mm

Index: ios/chrome/browser/net/mock_image_fetcher.mm
diff --git a/ios/chrome/browser/net/mock_image_fetcher.mm b/ios/chrome/browser/net/mock_image_fetcher.mm
deleted file mode 100644
index 7b02b8c8bea7908019e760fdb49d3a5212be2603..0000000000000000000000000000000000000000
--- a/ios/chrome/browser/net/mock_image_fetcher.mm
+++ /dev/null
@@ -1,13 +0,0 @@
-// 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.
-
-#import "ios/chrome/browser/net/mock_image_fetcher.h"
-
-MockImageFetcher::MockImageFetcher(
-    const scoped_refptr<base::TaskRunner>& task_runner)
-    : ImageFetcher(task_runner) {
-}
-
-MockImageFetcher::~MockImageFetcher() {
-}