[NTP::SectionOrder] Replace CategoryFactory with a category ranker.

components/ntp_snippets/remote/remote_suggestions_provider.cc

 // Copyright 2015 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/remote/remote_suggestions_provider.h"
 
 #include <algorithm>
 #include <iterator>
 #include <utility>
 
 #include "base/command_line.h"
 #include "base/feature_list.h"
 #include "base/location.h"
 #include "base/memory/ptr_util.h"
 #include "base/metrics/histogram_macros.h"
 #include "base/metrics/sparse_histogram.h"
 #include "base/path_service.h"
 #include "base/stl_util.h"
 #include "base/strings/string_number_conversions.h"
 #include "base/strings/utf_string_conversions.h"
 #include "base/task_runner_util.h"
 #include "base/time/default_clock.h"
 #include "base/time/default_tick_clock.h"
 #include "base/time/time.h"
 #include "base/values.h"
 #include "components/data_use_measurement/core/data_use_user_data.h"
 #include "components/history/core/browser/history_service.h"
 #include "components/image_fetcher/image_decoder.h"
 #include "components/image_fetcher/image_fetcher.h"
+#include "components/ntp_snippets/category_rankers/category_ranker.h"
 #include "components/ntp_snippets/features.h"
 #include "components/ntp_snippets/pref_names.h"
 #include "components/ntp_snippets/remote/remote_suggestions_database.h"
 #include "components/ntp_snippets/switches.h"
 #include "components/ntp_snippets/user_classifier.h"
 #include "components/prefs/pref_registry_simple.h"
 #include "components/prefs/pref_service.h"
 #include "components/variations/variations_associated_data.h"
 #include "grit/components_strings.h"
 #include "ui/base/l10n/l10n_util.h"
@@ skipping 177 matching lines @@
   if (callback.is_null()) {
     return;
   }
   callback.Run(status, std::vector<ContentSuggestion>());
 }
 
 }  // namespace
 
 RemoteSuggestionsProvider::RemoteSuggestionsProvider(
     Observer* observer,
-    CategoryFactory* category_factory,
     PrefService* pref_service,
     const std::string& application_language_code,
+    CategoryRanker* category_ranker,
     const UserClassifier* user_classifier,
     NTPSnippetsScheduler* scheduler,
     std::unique_ptr<NTPSnippetsFetcher> snippets_fetcher,
     std::unique_ptr<image_fetcher::ImageFetcher> image_fetcher,
     std::unique_ptr<image_fetcher::ImageDecoder> image_decoder,
     std::unique_ptr<RemoteSuggestionsDatabase> database,
     std::unique_ptr<RemoteSuggestionsStatusService> status_service)
-    : ContentSuggestionsProvider(observer, category_factory),
+    : ContentSuggestionsProvider(observer),
       state_(State::NOT_INITED),
       pref_service_(pref_service),
       articles_category_(
-          category_factory->FromKnownCategory(KnownCategories::ARTICLES)),
+          Category::FromKnownCategory(KnownCategories::ARTICLES)),
       application_language_code_(application_language_code),
+      category_ranker_(category_ranker),
       user_classifier_(user_classifier),
       scheduler_(scheduler),
       snippets_fetcher_(std::move(snippets_fetcher)),
       image_fetcher_(std::move(image_fetcher)),
       image_decoder_(std::move(image_decoder)),
       database_(std::move(database)),
       status_service_(std::move(status_service)),
       fetch_when_ready_(false),
       nuke_when_initialized_(false),
       thumbnail_requests_throttler_(
@@ skipping 338 matching lines @@
   DCHECK(base::ContainsKey(category_contents_, articles_category_));
 
   base::TimeDelta database_load_time =
       base::TimeTicks::Now() - database_load_start_;
   UMA_HISTOGRAM_MEDIUM_TIMES("NewTabPage.Snippets.DatabaseLoadTime",
                              database_load_time);
 
   NTPSnippet::PtrVector to_delete;
   for (std::unique_ptr<NTPSnippet>& snippet : snippets) {
     Category snippet_category =
-        category_factory()->FromRemoteCategory(snippet->remote_category_id());
+        Category::FromRemoteCategory(snippet->remote_category_id());
+    // The category is added to the ranker to enforce the order among remote
+    // categories.
+    category_ranker_->AppendCategoryIfNecessary(snippet_category);
     auto content_it = category_contents_.find(snippet_category);
     // We should already know about the category.
     if (content_it == category_contents_.end()) {
       DLOG(WARNING) << "Loaded a suggestion for unknown category "
                     << snippet_category << " from the DB; deleting";
       to_delete.emplace_back(std::move(snippet));
       continue;
     }
     CategoryContent* content = &content_it->second;
     if (snippet->is_dismissed()) {
@@ skipping 129 matching lines @@
     for (NTPSnippetsFetcher::FetchedCategory& fetched_category :
          *fetched_categories) {
       // TODO(tschumann): Remove this histogram once we only talk to the content
       // suggestions cloud backend.
       if (fetched_category.category == articles_category_) {
         UMA_HISTOGRAM_SPARSE_SLOWLY(
             "NewTabPage.Snippets.NumArticlesFetched",
             std::min(fetched_category.snippets.size(),
                      static_cast<size_t>(kMaxSnippetCount + 1)));
       }
+      category_ranker_->AppendCategoryIfNecessary(fetched_category.category);
       CategoryContent* content =
           UpdateCategoryInfo(fetched_category.category, fetched_category.info);
       content->included_in_last_server_response = true;
       SanitizeReceivedSnippets(content->dismissed, &fetched_category.snippets);
       IntegrateSnippets(content, std::move(fetched_category.snippets));
     }
   }
 
   // TODO(tschumann): The snippets fetcher needs to signal errors so that we
   // know why we received no data. If an error occured, none of the following
@@ skipping 524 matching lines @@
                           &included_in_last_server_response)) {
       DLOG(WARNING) << "Invalid category pref value, missing '"
                     << kCategoryContentProvidedByServer << "': " << *entry;
       continue;
     }
     bool allow_fetching_more_results = false;
     // This wasn't always around, so it's okay if it's missing.
     dict->GetBoolean(kCategoryContentAllowFetchingMore,
                      &allow_fetching_more_results);
 
-    Category category = category_factory()->FromIDValue(id);
+    Category category = Category::FromIDValue(id);
+    // The ranker may not persist the order of remote categories.
+    category_ranker_->AppendCategoryIfNecessary(category);
     // TODO(tschumann): The following has a bad smell that category
     // serialization / deserialization should not be done inside this
     // class. We should move that into a central place that also knows how to
     // parse data we received from remote backends.
     CategoryInfo info =
         category == articles_category_
             ? BuildArticleCategoryInfo(title)
             : BuildRemoteCategoryInfo(title, allow_fetching_more_results);
     CategoryContent* content = UpdateCategoryInfo(category, info);
     content->included_in_last_server_response =
         included_in_last_server_response;
   }
 }
 
 void RemoteSuggestionsProvider::StoreCategoriesToPrefs() {
   // Collect all the CategoryContents.
   std::vector<std::pair<Category, const CategoryContent*>> to_store;
   for (const auto& entry : category_contents_) {
     to_store.emplace_back(entry.first, &entry.second);
   }
-  // Sort them into the proper category order.
+  // The ranker may not persist the order, thus, it is stored by the provider.
   std::sort(to_store.begin(), to_store.end(),
             [this](const std::pair<Category, const CategoryContent*>& left,
                    const std::pair<Category, const CategoryContent*>& right) {
-              return category_factory()->CompareCategories(left.first,
-                                                           right.first);
+              return category_ranker_->Compare(left.first, right.first);
             });
   // Convert the relevant info into a base::ListValue for storage.
   base::ListValue list;
   for (const auto& entry : to_store) {
     const Category& category = entry.first;
     const CategoryContent& content = *entry.second;
     auto dict = base::MakeUnique<base::DictionaryValue>();
     dict->SetInteger(kCategoryContentId, category.id());
     // TODO(tschumann): Persist other properties of the CategoryInfo.
     dict->SetString(kCategoryContentTitle, content.info.title());
@@ skipping 14 matching lines @@
 RemoteSuggestionsProvider::CategoryContent::CategoryContent(CategoryContent&&) =
     default;
 
 RemoteSuggestionsProvider::CategoryContent::~CategoryContent() = default;
 
 RemoteSuggestionsProvider::CategoryContent&
 RemoteSuggestionsProvider::CategoryContent::operator=(CategoryContent&&) =
     default;
 
 }  // namespace ntp_snippets