Remove dom_utils.

content/renderer/dom_utils.h

-// Copyright 2014 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 CONTENT_RENDERER_DOM_UTILS_H_
-#define CONTENT_RENDERER_DOM_UTILS_H_
-
-namespace blink {
-class WebNode;
-}
-
-namespace content {
-
-class DomUtils {
- public:
-  // Walks up the DOM, looking for the first parent that represents an <a>.
-  // Returns a null WebNode if no such <a> exists.
-  static blink::WebNode ExtractParentAnchorNode(const blink::WebNode& node);
-};
-
-}  // namespace content
-
-#endif  // CONTENT_RENDERER_DOM_UTILS_H_