[Fallback Icons] Refactor FallbackIconService to be a BrowserContext-level singleton

chrome/browser/favicon/chrome_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 CHROME_BROWSER_FAVICON_CHROME_FALLBACK_ICON_CLIENT_H_
+#define CHROME_BROWSER_FAVICON_CHROME_FALLBACK_ICON_CLIENT_H_
+
+#include "components/favicon/core/browser/fallback_icon_client.h"
+
+#include <string>
+#include <vector>
+
+#include "base/macros.h"
+
+class GURL;
+class Profile;
+
+namespace favicon_base {
+class FallbackIconService;
+}  // namespace favicon_base
+
+// ChromeFallbackIconClient implements the the FallbackIconClient interface.
+class ChromeFallbackIconClient : public FallbackIconClient {
+ public:
+  explicit ChromeFallbackIconClient(Profile* profile);
+  ~ChromeFallbackIconClient() override;
+
+  // FallbackIconClient implementation:
+  favicon_base::FallbackIconService* GetFallbackIconService() override;
+  const std::vector<std::string>& GetFontNameList() override;
+
+ private:
+  Profile* profile_;
+
+  std::vector<std::string> font_list_;
+
+  DISALLOW_COPY_AND_ASSIGN(ChromeFallbackIconClient);
+};
+
+#endif  // CHROME_BROWSER_FAVICON_CHROME_FALLBACK_ICON_CLIENT_H_