Add a fallback to creation date for Recent bookmarks on NTP

components/ntp_snippets/bookmarks/bookmark_suggestions_provider.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_suggestions_provider.h"
 
 #include <utility>
 #include <vector>
 
 #include "base/bind.h"
@@ skipping 10 matching lines @@
 #include "grit/components_strings.h"
 #include "ui/base/l10n/l10n_util.h"
 #include "ui/gfx/image/image.h"
 
 using bookmarks::BookmarkModel;
 using bookmarks::BookmarkNode;
 
 namespace {
 
 const int kMaxBookmarks = 10;
+const int kMaxBookmarksIfNoVisitData = 3;
 const int kMaxBookmarkAgeInDays = 42;
 
 const char* kMaxBookmarksParamName = "max_count";
+const char* kMaxBookmarksIfNoVisitDataParamName = "max_count_no_visit_data";
 const char* kMaxBookmarkAgeInDaysParamName = "max_age_in_days";
 
-base::Time GetThresholdTime() {
+base::Time GetThresholdTime(bool no_visit_data) {
+  // If we have no data, we list bookmarks by creation date, no age limit.
+  if (no_visit_data)
+    return base::Time();
+
   std::string age_in_days_string = variations::GetVariationParamValueByFeature(
     ntp_snippets::kBookmarkSuggestionsFeature, kMaxBookmarkAgeInDaysParamName);
   int age_in_days = 0;
   if (!base::StringToInt(age_in_days_string, &age_in_days))
     age_in_days = kMaxBookmarkAgeInDays;
 
   return base::Time::Now() - base::TimeDelta::FromDays(age_in_days);
 }
 
-int GetMaxCount() {
+int GetMaxCount(bool no_visit_data) {
   std::string max_count_string = variations::GetVariationParamValueByFeature(
-    ntp_snippets::kBookmarkSuggestionsFeature, kMaxBookmarksParamName);
+      ntp_snippets::kBookmarkSuggestionsFeature,
+      no_visit_data ? kMaxBookmarksIfNoVisitDataParamName
+                    : kMaxBookmarksParamName);
   int max_count = 0;
   if (base::StringToInt(max_count_string, &max_count))
     return max_count;
 
-  return kMaxBookmarks;
+  return no_visit_data ? kMaxBookmarksIfNoVisitData : kMaxBookmarks;
 }
 
 }  // namespace
 
 namespace ntp_snippets {
 
 BookmarkSuggestionsProvider::BookmarkSuggestionsProvider(
     ContentSuggestionsProvider::Observer* observer,
     CategoryFactory* category_factory,
     bookmarks::BookmarkModel* bookmark_model)
     : ContentSuggestionsProvider(observer, category_factory),
       category_status_(CategoryStatus::AVAILABLE_LOADING),
       provided_category_(
           category_factory->FromKnownCategory(KnownCategories::BOOKMARKS)),
       bookmark_model_(bookmark_model),
       fetch_requested_(false),
-      end_of_list_last_visit_date_(GetThresholdTime()) {
+      no_visit_data_(false),
+      end_of_list_last_visit_date_(GetThresholdTime(no_visit_data_)) {
   bookmark_model_->AddObserver(this);
   FetchBookmarks();
 }
 
 BookmarkSuggestionsProvider::~BookmarkSuggestionsProvider() {
   bookmark_model_->RemoveObserver(this);
 }
 
 ////////////////////////////////////////////////////////////////////////////////
 // Private methods
@@ skipping 62 matching lines @@
   if (fetch_requested_) {
     fetch_requested_ = false;
     FetchBookmarksInternal();
   }
 }
 
 void BookmarkSuggestionsProvider::OnWillChangeBookmarkMetaInfo(
     BookmarkModel* model,
     const BookmarkNode* node) {
   // Store the last visit date of the node that is about to change.
-  node_to_change_last_visit_date_ =
-      GetLastVisitDateForBookmarkIfNotDismissed(node);
+  node_to_change_last_visit_date_ = GetLastVisitDateForBookmarkIfNotDismissed(
+      node, no_visit_data_);
 }
 
 void BookmarkSuggestionsProvider::BookmarkMetaInfoChanged(
     BookmarkModel* model,
     const BookmarkNode* node) {
-  base::Time time = GetLastVisitDateForBookmarkIfNotDismissed(node);
+  base::Time time = GetLastVisitDateForBookmarkIfNotDismissed(
+      node, no_visit_data_);
   if (time == node_to_change_last_visit_date_ ||
       time < end_of_list_last_visit_date_)
     return;
 
   // Last visit date of a node has changed (and is relevant for the list), we
   // should update the suggestions.
   FetchBookmarks();
 }
 
 void BookmarkSuggestionsProvider::BookmarkNodeRemoved(
       bookmarks::BookmarkModel* model,
       const bookmarks::BookmarkNode* parent,
       int old_index,
       const bookmarks::BookmarkNode* node,
       const std::set<GURL>& no_longer_bookmarked) {
-  if (GetLastVisitDateForBookmarkIfNotDismissed(node) <
+  if (GetLastVisitDateForBookmarkIfNotDismissed(node, no_visit_data_) <
       end_of_list_last_visit_date_)
     return;
 
   // Some node from our list got deleted, we should update the suggestions.
   FetchBookmarks();
 }
 
 ContentSuggestion BookmarkSuggestionsProvider::ConvertBookmark(
     const BookmarkNode* bookmark) {
   ContentSuggestion suggestion(
       MakeUniqueID(provided_category_, bookmark->url().spec()),
       bookmark->url());
 
   suggestion.set_title(bookmark->GetTitle());
   suggestion.set_snippet_text(base::string16());
-  suggestion.set_publish_date(GetLastVisitDateForBookmark(bookmark));
+  suggestion.set_publish_date(
+      GetLastVisitDateForBookmark(bookmark, no_visit_data_));
   suggestion.set_publisher_name(base::UTF8ToUTF16(bookmark->url().host()));
   return suggestion;
 }
 
 void BookmarkSuggestionsProvider::FetchBookmarksInternal() {
   DCHECK(bookmark_model_->loaded());
 
   NotifyStatusChanged(CategoryStatus::AVAILABLE);
 
-  base::Time threshold_time = GetThresholdTime();
+  no_visit_data_ = !IsLastVisitDataAvailable(bookmark_model_);

[Marc Treib, 2016/08/17 11:29:06]

Hm, so this means, a new user will get 3 bookmarks. They visit one of them, and
now they only get a single one (because the other two have creation dates more
than 6 weeks ago).
Is that the behavior we want? I think I'd be happier with some form of graceful
fallback, rather than this hard switch between two modes.

+
+  base::Time threshold_time = GetThresholdTime(no_visit_data_);
   std::vector<const BookmarkNode*> bookmarks = GetRecentlyVisitedBookmarks(
-      bookmark_model_, GetMaxCount(), threshold_time);
+      bookmark_model_, no_visit_data_, GetMaxCount(no_visit_data_),
+      threshold_time);
 
   std::vector<ContentSuggestion> suggestions;
   for (const BookmarkNode* bookmark : bookmarks)
     suggestions.emplace_back(ConvertBookmark(bookmark));
 
   if (suggestions.empty())
     end_of_list_last_visit_date_ = threshold_time;
   else
     end_of_list_last_visit_date_ = suggestions.back().publish_date();
 
@@ skipping 10 matching lines @@
 
 void BookmarkSuggestionsProvider::NotifyStatusChanged(
     CategoryStatus new_status) {
   if (category_status_ == new_status)
     return;
   category_status_ = new_status;
   observer()->OnCategoryStatusChanged(this, provided_category_, new_status);
 }
 
 }  // namespace ntp_snippets