[NTP Snippets] Metrics: switch over known categories

components/ntp_snippets/category_factory.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/category_factory.h"
 
 #include <algorithm>
 
 #include "base/logging.h"
 
 namespace ntp_snippets {
 
 CategoryFactory::CategoryFactory() {
   // Add all local categories in a fixed order.
   AddKnownCategory(KnownCategories::DOWNLOADS);
   AddKnownCategory(KnownCategories::RECENT_TABS);
   AddKnownCategory(KnownCategories::BOOKMARKS);
   AddKnownCategory(KnownCategories::PHYSICAL_WEB_PAGES);
+
+  DCHECK_EQ(static_cast<size_t>(KnownCategories::LOCAL_CATEGORIES_COUNT),
+            ordered_categories_.size());
 }
 
 CategoryFactory::~CategoryFactory() {}
 
 Category CategoryFactory::FromKnownCategory(KnownCategories known_category) {
   if (known_category < KnownCategories::LOCAL_CATEGORIES_COUNT) {
     // Local categories should have been added already.
     DCHECK(CategoryExists(static_cast<int>(known_category)));
   } else {
     DCHECK_GT(known_category, KnownCategories::REMOTE_CATEGORIES_OFFSET);
@@ skipping 41 matching lines @@
                       Category(id));
   if (it != ordered_categories_.end())
     return *it;
 
   Category category(id);
   ordered_categories_.push_back(category);
   return category;
 }
 
 }  // namespace ntp_snippets