Add a tab helper to record the last visit date for each bookmark.

components/ntp_snippets/bookmarks/bookmark_last_visit_utils.cc

+// 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.
+
+#include "components/ntp_snippets/bookmarks/bookmark_last_visit_utils.h"
+
+#include <algorithm>
+#include <string>
+#include <utility>
+
+#include "base/strings/string_number_conversions.h"
+
+using bookmarks::BookmarkModel;
+using bookmarks::BookmarkNode;
+
+namespace {
+
+const char kBookmarkLastVisitDateKey[] = "last_visited";
+
+base::Time ParseLastVisitDate(const std::string& date_string) {
+  int64_t date = 0;
+  if (!base::StringToInt64(date_string, &date))
+    return base::Time::UnixEpoch();
+  return base::Time::FromInternalValue(date);
+}
+
+std::string FormatLastVisitDate(const base::Time& date) {
+  return base::Int64ToString(date.ToInternalValue());
+}
+
+bool CompareBookmarksByLastVisitDate(const BookmarkNode* a,
+                                    const BookmarkNode* b) {

[Marc Treib, 2016/07/29 14:36:43]

misaligned

[jkrcal, 2016/07/29 15:34:07]

Done.

+  return (ntp_snippets::GetLastVisitDateForBookmark(a) -
+          ntp_snippets::GetLastVisitDateForBookmark(b))

[Marc Treib, 2016/07/29 14:36:42]

optionally, you could move the anonymous namespace into the ntp_snippets
namespace, then you don't have to say "ntp_snippets::" here.

[jkrcal, 2016/07/29 15:34:07]

Done.

+             .InMilliseconds() > 0;
+}
+
+}  // namespace
+
+namespace ntp_snippets {
+
+void UpdateBookmarkOnURLVisitedInMainFrame(
+    BookmarkModel* bookmark_model,

[Marc Treib, 2016/07/29 14:36:43]

fits on the previous line?

[jkrcal, 2016/07/29 15:34:07]

Done.

+    const GURL& url) {
+  const BookmarkNode* node =
+      bookmark_model->GetMostRecentlyAddedUserNodeForURL(url);
+  if (!node)
+    return;
+
+  // If there exists a bookmark for |url|, set its last visit date to now.
+  bookmark_model->SetNodeMetaInfo(node, kBookmarkLastVisitDateKey,
+                                  FormatLastVisitDate(base::Time::Now()));
+}
+
+base::Time GetLastVisitDateForBookmark(
+    const BookmarkNode* node) {

[Marc Treib, 2016/07/29 14:36:42]

fits on the previous line?

[jkrcal, 2016/07/29 15:34:07]

Done.

+  if (!node)
+    return base::Time::UnixEpoch();
+
+  std::string last_visit_date_string;
+  node->GetMetaInfo(kBookmarkLastVisitDateKey, &last_visit_date_string);
+
+  if (last_visit_date_string.empty()) {
+    // Use creation date if no last visit info present.
+    return node->date_added();
+  }
+
+  return ParseLastVisitDate(last_visit_date_string);
+}
+
+std::vector<const BookmarkNode*> GetRecentlyVisitedBookmarks(
+    BookmarkModel* bookmark_model,
+    int max_count,
+    const base::Time& min_visit_time) {
+  // Get all the bookmarks.
+  std::vector<BookmarkModel::URLAndTitle> all_bookmarks;

[Marc Treib, 2016/07/29 14:36:43]

nit: I'd just call this bookmarks, since you filter some out, so it's not all
anymore.

[jkrcal, 2016/07/29 15:34:07]

Done.

+  bookmark_model->GetBookmarks(&all_bookmarks);
+  // Remove bookmarks that have not been visited after |min_time|.
+  all_bookmarks.erase(
+      std::remove_if(
+          all_bookmarks.begin(), all_bookmarks.end(),
+          [&bookmark_model,
+           &min_visit_time](const BookmarkModel::URLAndTitle& bookmark) {
+            return GetLastVisitDateForBookmark(
+                       bookmark_model->GetMostRecentlyAddedUserNodeForURL(
+                           bookmark.url)) < min_visit_time;
+          }),
+      all_bookmarks.end());
+  // Sort the remaining bookmarks by date.
+  std::sort(all_bookmarks.begin(), all_bookmarks.end(),
+            [&bookmark_model](const BookmarkModel::URLAndTitle& a,
+                const BookmarkModel::URLAndTitle& b) {
+              return CompareBookmarksByLastVisitDate(
+                  bookmark_model->GetMostRecentlyAddedUserNodeForURL(a.url),
+                  bookmark_model->GetMostRecentlyAddedUserNodeForURL(b.url));
+            });
+
+  std::vector<const BookmarkNode*> bookmarks;

[Marc Treib, 2016/07/29 14:36:43]

Ah, then you'll also have to rename this... result maybe?

[jkrcal, 2016/07/29 15:34:07]

Done.

+  // Insert the first |max_count| into |bookmarks|.
+  for (const BookmarkModel::URLAndTitle& bookmark : all_bookmarks) {
+    bookmarks.push_back(
+        bookmark_model->GetMostRecentlyAddedUserNodeForURL(bookmark.url));
+    if (bookmarks.size() >= (unsigned) max_count)

[Marc Treib, 2016/07/29 14:36:43]

static_cast<size_t> ? It's ugly, but at least it's honest, and we don't use
unsigned.

[jkrcal, 2016/07/29 15:34:07]

Done.

+      break;
+  }
+  return bookmarks;
+}
+
+}  // namespace ntp_snippets