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

[sky, 2016/08/01 15:15:47]

Generally we name these classes with TabHelper at the end, e.g.
BookmarkLastVisitUpdateTabHelper or maybe just BookmarkLastUpdateTabHelper.

[tschumann, 2016/08/01 16:57:26]

:-) In the initial rounds of the review, we just had the reverse naming
discussion (Jan was suggesting a 'Helper' name). I argued against it as helpers
don't add any value to the name.
It's purpose is to update the Bookmark's last-visit information so why not just
call it after what it does.

I realize that consistency also adds value, so if you insist we can change the
name (although codesearch shows many naming flavors =)). It's just that from our
code's point of view a 'TabHelper' suffix might actually be misleading and
unnecessarily expose implementation details.

Thanks for the review!

--Tim

[Philipp Keck, 2016/08/02 13:05:33]

Acknowledged. Leaving as is for the moment, since Avi hasn't responded yet.

+    : public content::WebContentsObserver,
+      public content::WebContentsUserData<BookmarkLastVisitUpdater> {
+ public:
+  ~BookmarkLastVisitUpdater() override;
+
+  static void CreateForWebContentsWithBookmarkModel(
+      content::WebContents* web_contents,
+      bookmarks::BookmarkModel* bookmark_model);
+
+ private:
+  explicit BookmarkLastVisitUpdater(
+      content::WebContents* web_contents,
+      bookmarks::BookmarkModel* bookmark_model);
+  friend class content::WebContentsUserData<BookmarkLastVisitUpdater>;
+
+  // 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_