[Soft fetches] Set-up different intervals for <Chrome started> events.

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 Chrome) when there is a WiFi connectivity.
-extern const char kSnippetSoftFetchingIntervalWifi[];
-// The pref name for the currently applied minimal interval between two
-// successive soft background fetches that react to user activity (such as
-// opening Chrome) when there is no WiFi connectivity.
-extern const char kSnippetSoftFetchingIntervalFallback[];
 
-// The pref name for the currently-scheduled background fetching interval when
-// there is WiFi connectivity.
+// Pref names for minimal intervals between two successive background fetches.
+//
+// The prefs store *currently applied* minimal intervals. For each trigger type
+// there are two intervals stored in prefs:
+//  - "Wifi" for situations with Wifi / unmetered network connectivity, and
+//  - "Fallback" for situations with only non-Wifi / metered network.
+// We check "meteredness" of the current network only on platforms that support
+// that, notably Android; we use WiFi as the proxy of being unmetered elsewhere.
+//
+// Intervals for trigger type 1: wake-up of the persistent scheduler.
 extern const char kSnippetPersistentFetchingIntervalWifi[];
-// The pref name for the currently-scheduled background fetching interval when
-// there is no WiFi connectivity.
 extern const char kSnippetPersistentFetchingIntervalFallback[];
+// Intervals for trigger type 2: browser started-up (both cold and warm start).
+extern const char kSnippetStartupFetchingIntervalWifi[];
+extern const char kSnippetStartupFetchingIntervalFallback[];
+// Intervals for trigger type 3: suggestions shown to the user.
+extern const char kSnippetShownFetchingIntervalWifi[];
+extern const char kSnippetShownFetchingIntervalFallback[];
 
 // The pref name for today's count of RemoteSuggestionsFetcher requests, so far.
 extern const char kSnippetFetcherRequestCount[];
 // The pref name for today's count of RemoteSuggestionsFetcher interactive
 // requests.
 extern const char kSnippetFetcherInteractiveRequestCount[];
 // The pref name for the current day for the counter of RemoteSuggestionsFetcher
 // requests.
 extern const char kSnippetFetcherRequestsDay[];
 
@@ skipping 37 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_