[NTP Snippets] Persist remote categories in prefs

components/ntp_snippets/remote/ntp_snippets_service.cc

Index: components/ntp_snippets/remote/ntp_snippets_service.cc
diff --git a/components/ntp_snippets/remote/ntp_snippets_service.cc b/components/ntp_snippets/remote/ntp_snippets_service.cc
index 78aea3a04b60edba453d0f2562906971ae05a88e..7c7cc1fbaf237941592e2134048e510b29c85c18 100644
--- a/components/ntp_snippets/remote/ntp_snippets_service.cc
+++ b/components/ntp_snippets/remote/ntp_snippets_service.cc
@@ -193,12 +193,19 @@ NTPSnippetsService::NTPSnippetsService(
       thumbnail_requests_throttler_(
           pref_service,
           RequestThrottler::RequestType::CONTENT_SUGGESTION_THUMBNAIL) {
-  // Articles category always exists; others will be added as needed.
-  categories_[articles_category_] = CategoryContent();
-  categories_[articles_category_].localized_title =
-      l10n_util::GetStringUTF16(IDS_NTP_ARTICLE_SUGGESTIONS_SECTION_HEADER);
-  observer->OnCategoryStatusChanged(this, articles_category_,
-                                    categories_[articles_category_].status);
+  RestoreCategoriesFromPrefs();
+  // The articles category always exists. Add it if we didn't get it from prefs.
+  // TODO(treib): Rethink this.
+  if (!base::ContainsKey(categories_, articles_category_)) {
+    categories_[articles_category_] = CategoryContent();
+    categories_[articles_category_].localized_title =
+        l10n_util::GetStringUTF16(IDS_NTP_ARTICLE_SUGGESTIONS_SECTION_HEADER);
+  }
+  // Tell the observer about all the categories.
+  for (const auto& entry : categories_) {
+    observer->OnCategoryStatusChanged(this, entry.first, entry.second.status);
+  }
+
   if (database_->IsErrorState()) {
     EnterState(State::ERROR_OCCURRED);
     UpdateAllCategoryStatus(CategoryStatus::LOADING_ERROR);
@@ -218,7 +225,10 @@ NTPSnippetsService::~NTPSnippetsService() = default;
 
 // static
 void NTPSnippetsService::RegisterProfilePrefs(PrefRegistrySimple* registry) {
-  registry->RegisterListPref(prefs::kSnippetHosts); //TODO remove
+  // TODO(treib): Add cleanup logic for prefs::kSnippetHosts, then remove it
+  // completely after M56.
+  registry->RegisterListPref(prefs::kSnippetHosts);
+  registry->RegisterListPref(prefs::kRemoteSuggestionCategories);
   registry->RegisterInt64Pref(prefs::kSnippetBackgroundFetchingIntervalWifi, 0);
   registry->RegisterInt64Pref(prefs::kSnippetBackgroundFetchingIntervalFallback,
                               0);
@@ -299,12 +309,12 @@ void NTPSnippetsService::RescheduleFetching(bool force) {
 }
 
 CategoryStatus NTPSnippetsService::GetCategoryStatus(Category category) {
-  DCHECK(categories_.find(category) != categories_.end());
+  DCHECK(base::ContainsKey(categories_, category));
   return categories_[category].status;
 }
 
 CategoryInfo NTPSnippetsService::GetCategoryInfo(Category category) {
-  DCHECK(categories_.find(category) != categories_.end());
+  DCHECK(base::ContainsKey(categories_, category));
   const CategoryContent& content = categories_[category];
   return CategoryInfo(content.localized_title,
                       ContentSuggestionsCardLayout::FULL_CARD,
@@ -363,7 +373,7 @@ void NTPSnippetsService::ClearCachedSuggestions(Category category) {
   if (!initialized())
     return;
 
-  if (categories_.find(category) == categories_.end())
+  if (!base::ContainsKey(categories_, category))
     return;
   CategoryContent* content = &categories_[category];
   if (content->snippets.empty())
@@ -381,7 +391,7 @@ void NTPSnippetsService::ClearCachedSuggestions(Category category) {
 void NTPSnippetsService::GetDismissedSuggestionsForDebugging(
     Category category,
     const DismissedSuggestionsCallback& callback) {
-  DCHECK(categories_.find(category) != categories_.end());
+  DCHECK(base::ContainsKey(categories_, category));
 
   std::vector<ContentSuggestion> result;
   const CategoryContent& content = categories_[category];
@@ -404,7 +414,7 @@ void NTPSnippetsService::GetDismissedSuggestionsForDebugging(
 
 void NTPSnippetsService::ClearDismissedSuggestionsForDebugging(
     Category category) {
-  DCHECK(categories_.find(category) != categories_.end());
+  DCHECK(base::ContainsKey(categories_, category));
 
   if (!initialized())
     return;
@@ -430,7 +440,7 @@ int NTPSnippetsService::GetMaxSnippetCountForTesting() {
 
 GURL NTPSnippetsService::FindSnippetImageUrl(
     const ContentSuggestion::ID& suggestion_id) const {
-  DCHECK(categories_.find(suggestion_id.category()) != categories_.end());
+  DCHECK(base::ContainsKey(categories_, suggestion_id.category()));
 
   const CategoryContent& content = categories_.at(suggestion_id.category());
   const NTPSnippet* snippet =
@@ -467,10 +477,9 @@ void NTPSnippetsService::OnDatabaseLoaded(NTPSnippet::PtrVector snippets) {
   if (state_ == State::ERROR_OCCURRED)
     return;
   DCHECK(state_ == State::NOT_INITED);
-  DCHECK_EQ(1u, categories_.size());  // Only articles category, so far.
-  DCHECK(categories_.find(articles_category_) != categories_.end());
+  DCHECK(base::ContainsKey(categories_, articles_category_));
 
-  // TODO(sfiera): support non-article categories in database.
+  // TODO(treib): Support non-article categories in database. crbug.com/653476
   CategoryContent* content = &categories_[articles_category_];
   for (std::unique_ptr<NTPSnippet>& snippet : snippets) {
     if (snippet->is_dismissed())
@@ -503,6 +512,8 @@ void NTPSnippetsService::OnFetchFinished(
   if (!ready())
     return;
 
+  // Mark all categories as not provided by the server in the latest fetch. The
+  // ones we got will be marked again below.
   for (auto& item : categories_) {
     CategoryContent* content = &item.second;
     content->provided_by_server = false;
@@ -545,6 +556,10 @@ void NTPSnippetsService::OnFetchFinished(
     }
   }
 
+  // We might have gotten new categories (or updated the titles of existing
+  // ones), so update the pref.
+  StoreCategoriesToPrefs();
+
   for (const auto& item : categories_) {
     Category category = item.first;
     UpdateCategoryStatus(category, CategoryStatus::AVAILABLE);
@@ -574,7 +589,7 @@ void NTPSnippetsService::ArchiveSnippets(Category category,
                                          NTPSnippet::PtrVector* to_archive) {
   CategoryContent* content = &categories_[category];
 
-  // TODO(sfiera): handle DB for non-articles too.
+  // TODO(treib): Handle DB for non-articles too. crbug.com/653476
   if (category == articles_category_) {
     database_->DeleteSnippets(GetSnippetIDVector(*to_archive));
     // Do not delete the thumbnail images as they are still handy on open NTPs.
@@ -692,6 +707,8 @@ void NTPSnippetsService::ClearExpiredDismissedSnippets() {
     UpdateCategoryStatus(category, CategoryStatus::NOT_PROVIDED);
     categories_.erase(category);
   }
+
+  StoreCategoriesToPrefs();
 }
 
 void NTPSnippetsService::ClearOrphanedImages() {
@@ -726,6 +743,8 @@ void NTPSnippetsService::NukeAllSnippets() {
   for (Category category : categories_to_erase) {
     categories_.erase(category);
   }
+
+  StoreCategoriesToPrefs();
 }
 
 void NTPSnippetsService::OnSnippetImageFetchedFromDatabase(
@@ -762,7 +781,7 @@ void NTPSnippetsService::OnSnippetImageDecodedFromDatabase(
 void NTPSnippetsService::FetchSnippetImageFromNetwork(
     const ContentSuggestion::ID& suggestion_id,
     const ImageFetchedCallback& callback) {
-  if (categories_.find(suggestion_id.category()) == categories_.end()) {
+  if (!base::ContainsKey(categories_, suggestion_id.category())) {
     OnSnippetImageDecodedFromNetwork(
         callback, suggestion_id.id_within_category(), gfx::Image());
     return;
@@ -967,7 +986,7 @@ void NTPSnippetsService::NotifyNewSuggestions() {
 
 void NTPSnippetsService::UpdateCategoryStatus(Category category,
                                               CategoryStatus status) {
-  DCHECK(categories_.find(category) != categories_.end());
+  DCHECK(base::ContainsKey(categories_, category));
   CategoryContent& content = categories_[category];
   if (status == content.status)
     return;
@@ -1007,6 +1026,81 @@ const NTPSnippet* NTPSnippetsService::CategoryContent::FindSnippet(
   return nullptr;
 }
 
+namespace {
+
+const char kCategoryContentId[] = "id";
+const char kCategoryContentTitle[] = "title";
+const char kCategoryContentProvidedByServer[] = "provided_by_server";
+
+}  // namespace
+
+void NTPSnippetsService::RestoreCategoriesFromPrefs() {
+  // This must only be called at startup, before there are any categories.
+  DCHECK(categories_.empty());
+
+  const base::ListValue* list =
+      pref_service_->GetList(prefs::kRemoteSuggestionCategories);
+  for (const std::unique_ptr<base::Value>& entry : *list) {
+    const base::DictionaryValue* dict = nullptr;
+    if (!entry->GetAsDictionary(&dict)) {
+      DLOG(WARNING) << "Invalid category pref value: " << *entry;
+      continue;
+    }
+    int id = 0;
+    if (!dict->GetInteger(kCategoryContentId, &id)) {
+      DLOG(WARNING) << "Invalid category pref value, missing '"
+                    << kCategoryContentId << "': " << *entry;
+      continue;
+    }
+    base::string16 title;
+    if (!dict->GetString(kCategoryContentTitle, &title)) {
+      DLOG(WARNING) << "Invalid category pref value, missing '"
+                    << kCategoryContentTitle << "': " << *entry;
+      continue;
+    }
+    bool provided_by_server = false;
+    if (!dict->GetBoolean(kCategoryContentProvidedByServer,
+                          &provided_by_server)) {
+      DLOG(WARNING) << "Invalid category pref value, missing '"
+                    << kCategoryContentProvidedByServer << "': " << *entry;
+      continue;
+    }
+
+    Category category = category_factory()->FromIDValue(id);
+    categories_[category] = CategoryContent();
+    categories_[category].localized_title = title;
+    categories_[category].provided_by_server = provided_by_server;
+  }
+}
+
+void NTPSnippetsService::StoreCategoriesToPrefs() {
+  // Collect all the CategoryContents.
+  std::vector<std::pair<Category, const CategoryContent*>> to_store;
+  for (const auto& entry : categories_)
+    to_store.emplace_back(entry.first, &entry.second);
+  // Sort them into the proper category order.
+  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);
+            });
+  // Convert the relevant info into a base::ListValue for storage.
+  base::ListValue list;
+  for (const auto& entry : to_store) {
+    Category category = entry.first;
+    const base::string16& title = entry.second->localized_title;
+    bool provided_by_server = entry.second->provided_by_server;
+    auto dict = base::MakeUnique<base::DictionaryValue>();
+    dict->SetInteger(kCategoryContentId, category.id());
+    dict->SetString(kCategoryContentTitle, title);
+    dict->SetBoolean(kCategoryContentProvidedByServer, provided_by_server);
+    list.Append(std::move(dict));
+  }
+  // Finally, store the result in the pref service.
+  pref_service_->Set(prefs::kRemoteSuggestionCategories, list);
+}
+
 NTPSnippetsService::CategoryContent::CategoryContent() = default;
 NTPSnippetsService::CategoryContent::CategoryContent(CategoryContent&&) =
     default;