[Background fetching] Background fetching when opening an NTP.

components/ntp_snippets/pref_names.h

 // 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.
 
 #ifndef COMPONENTS_NTP_SNIPPETS_PREF_NAMES_H_
 #define COMPONENTS_NTP_SNIPPETS_PREF_NAMES_H_
 
 namespace ntp_snippets {
 namespace prefs {
 
 // If set to false, remote suggestions are completely disabled. This is set by
 // an enterprise policy.
 extern const char kEnableSnippets[];
 
 // The pref name under which remote suggestion categories (including their ID
 // and title) are stored.
 extern const char kRemoteSuggestionCategories[];
 
+// The pref name for the last time when a background fetch was attempted.
+extern const char kSnippetLastFetchAttempt[];
+// The pref name for the currently applied minimal interval between two
+// successive soft background fetches that react to user activity (such as
+// opening an NTP).
+extern const char kSnippetSoftFetchingIntervalOnUsageEvent[];
+
 // The pref name for the currently-scheduled background fetching interval when
 // there is WiFi connectivity.
-extern const char kSnippetBackgroundFetchingIntervalWifi[];
+extern const char kSnippetPersistentFetchingIntervalWifi[];
 // The pref name for the currently-scheduled background fetching interval when
 // there is no WiFi connectivity.
-extern const char kSnippetBackgroundFetchingIntervalFallback[];
+extern const char kSnippetPersistentFetchingIntervalFallback[];
 
 // The pref name for today's count of NTPSnippetsFetcher requests, so far.
 extern const char kSnippetFetcherRequestCount[];
 // The pref name for today's count of NTPSnippetsFetcher interactive requests.
 extern const char kSnippetFetcherInteractiveRequestCount[];
 // The pref name for the current day for the counter of NTPSnippetsFetcher
 // requests.
 extern const char kSnippetFetcherRequestsDay[];
 
 // The pref name for today's count of requests for article thumbnails, so far.
@@ skipping 36 matching lines @@
 
 // The pref name for the current order of categories and their clicks.
 extern const char kClickBasedCategoryRankerOrderWithClicks[];
 // The pref name for the time when last click decay has happened.
 extern const char kClickBasedCategoryRankerLastDecayTime[];
 
 }  // namespace prefs
 }  // namespace ntp_snippets
 
 #endif  // COMPONENTS_NTP_SNIPPETS_PREF_NAMES_H_