[New CL] Add a tab helper to record the last visit date for each bookmark

chrome/browser/ntp_snippets/bookmark_last_visit_updater.h

Index: chrome/browser/ntp_snippets/bookmark_last_visit_updater.h
diff --git a/chrome/browser/ntp_snippets/bookmark_last_visit_updater.h b/chrome/browser/ntp_snippets/bookmark_last_visit_updater.h
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+// Copyright 2016 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_NTP_SNIPPETS_BOOKMARK_LAST_VISIT_UPDATER_H_
+#define CHROME_BROWSER_NTP_SNIPPETS_BOOKMARK_LAST_VISIT_UPDATER_H_
+
+#include <memory>
+
+#include "base/macros.h"
+#include "content/public/browser/web_contents_observer.h"
+#include "content/public/browser/web_contents_user_data.h"
+
+namespace bookmarks {
+class BookmarkModel;
+}  // namespace bookmarks
+
+namespace content {
+class NavigationHandle;
+class WebContents;
+}  // namespace content
+
+// A bridge class between platform-specific content::WebContentsObserver and the
+// generic function ntp_snippets::UpdateBookmarkOnURLVisitedInMainFrame().
+class BookmarkLastVisitUpdater
+    : public content::WebContentsObserver,
+      public content::WebContentsUserData<BookmarkLastVisitUpdater> {
+ public:
+  ~BookmarkLastVisitUpdater() override;
+
+  static void CreateForWebContentsWithBookmarkModel(
+      content::WebContents* web_contents,
+      bookmarks::BookmarkModel* bookmark_model);
+
+ private:
+  friend class content::WebContentsUserData<BookmarkLastVisitUpdater>;
+
+  BookmarkLastVisitUpdater(content::WebContents* web_contents,
+                           bookmarks::BookmarkModel* bookmark_model);
+
+  // Overridden from content::WebContentsObserver:
+  void DidStartNavigation(
+      content::NavigationHandle* navigation_handle) override;
+
+  bookmarks::BookmarkModel* bookmark_model_;
+
+  DISALLOW_COPY_AND_ASSIGN(BookmarkLastVisitUpdater);
+};
+
+#endif  // CHROME_BROWSER_NTP_SNIPPETS_BOOKMARK_LAST_VISIT_UPDATER_H_