Delete unused chrome://fallback-icon/ handling

components/favicon/core/fallback_icon_client.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 COMPONENTS_FAVICON_CORE_FALLBACK_ICON_CLIENT_H_
-#define COMPONENTS_FAVICON_CORE_FALLBACK_ICON_CLIENT_H_
-
-#include <string>
-#include <vector>
-
-#include "components/keyed_service/core/keyed_service.h"
-
-namespace favicon {
-
-// This class abstracts operations that depend on the embedder's environment,
-// e.g. Chrome.
-class FallbackIconClient : public KeyedService {
- public:
-  // Returns a list of font names for fallback icon rendering.
-  virtual const std::vector<std::string>& GetFontNameList() const = 0;
-
- protected:
-  ~FallbackIconClient() override {}
-};
-
-}  // namespace favicon
-
-#endif  // COMPONENTS_FAVICON_CORE_FALLBACK_ICON_CLIENT_H_