Add request throttler to thumbnail fetching for articles on mobile NTP

components/ntp_snippets/pref_names.h

Index: components/ntp_snippets/pref_names.h
diff --git a/components/ntp_snippets/pref_names.h b/components/ntp_snippets/pref_names.h
index 4fdea4ebba7065ad0935aa66825b9bf055e1dc6a..e07ca2c7b597f1945cae1feb6dfb14b5bc4e1a19 100644
--- a/components/ntp_snippets/pref_names.h
+++ b/components/ntp_snippets/pref_names.h
@@ -14,10 +14,20 @@ 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