Add request throttler to thumbnail fetching for articles on mobile 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 {
 
 extern const char kEnableSnippets[];
 
 extern const char kSnippetHosts[];
 
 // The pref name for today's count of NTPSnippetsFetcher requests, so far.
 extern const char kSnippetFetcherQuotaCount[];
+// The pref name for today's count of NTPSnippetsFetcher interactive requests.
+extern const char kSnippetFetcherInteractiveQuotaCount[];

[Marc Treib, 2016/08/09 14:04:53]

I still think we should remove "Quota" from these names; I get confused every
time I read this. How about kSnippetFetcherRequestCount,
kSnippetFetcherInteractiveRequestCount etc?

[jkrcal, 2016/08/10 10:27:26]

Done.

 // The pref name for the current day for the counter of NTPSnippetsFetcher
 // requests.
 extern const char kSnippetFetcherQuotaDay[];
 
+// The pref name for today's count of NTPSnippetsFetcher requests, so far.
+extern const char kSnippetThumbnailsQuotaCount[];
+// The pref name for today's count of NTPSnippetsFetcher requests, so far.
+extern const char kSnippetThumbnailsInteractiveQuotaCount[];
+// The pref name for the current day for the counter of NTPSnippetsFetcher
+// requests.
+extern const char kSnippetThumbnailsQuotaDay[];
+
 }  // namespace prefs
 }  // namespace ntp_snippets
 
 #endif  // COMPONENTS_NTP_SNIPPETS_PREF_NAMES_H_