Abstract history dependencies on bookmarks through HistoryClient

chrome/browser/history/chrome_history_client.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 CHROME_BROWSER_HISTORY_CHROME_HISTORY_CLIENT_H_
 #define CHROME_BROWSER_HISTORY_CHROME_HISTORY_CLIENT_H_
 
 #include "base/macros.h"
 #include "components/history/core/browser/history_client.h"
 
+class BookmarkModel;
+
+// This class implements history::HistoryClient to abstract operations that
+// depend on Chrome environment.
 class ChromeHistoryClient : public history::HistoryClient {
  public:
-  ChromeHistoryClient();
+  explicit ChromeHistoryClient(BookmarkModel* bookmark_model);
 
- protected:
+  // history::HistoryClient:
+  virtual void BlockUntilBookmarksLoaded() OVERRIDE;
+  virtual bool IsBookmarked(const GURL& url) OVERRIDE;
+  virtual void GetBookmarks(
+      std::vector<history::URLAndTitle>* bookmarks) OVERRIDE;
+
+  // KeyedService:
+  virtual void Shutdown() OVERRIDE;
+
+ private:
+  // The BookmarkModel, this should outlive ChromeHistoryClient.
+  BookmarkModel* bookmark_model_;
+
   DISALLOW_COPY_AND_ASSIGN(ChromeHistoryClient);
 };
 
 #endif  // CHROME_BROWSER_HISTORY_CHROME_HISTORY_CLIENT_H_