Adding a request counter to the snippets fetcher.

components/ntp_snippets/ntp_snippets_fetcher.cc

Index: components/ntp_snippets/ntp_snippets_fetcher.cc
diff --git a/components/ntp_snippets/ntp_snippets_fetcher.cc b/components/ntp_snippets/ntp_snippets_fetcher.cc
index 5869644f963492b331dfbcc2dc5eb70accf87db8..255bc88dd7ca6cb1e5be7afc54c9008e9307afaf 100644
--- a/components/ntp_snippets/ntp_snippets_fetcher.cc
+++ b/components/ntp_snippets/ntp_snippets_fetcher.cc
@@ -76,6 +76,8 @@ const char kPersonalizationBothString[] = "both";  // the default value
 const char kHostRestrictionOnString[] = "on";  // the default value
 const char kHostRestrictionOffString[] = "off";
 
+const int kArticlesQuotaPerDay = 20;

[Marc Treib, 2016/07/22 13:52:52]

This sounds like "number of articles per day", but it's actually the number of
fetches.

Also, should we build in the option to override this via variation params?

[jkrcal, 2016/07/25 10:05:38]

Done.

Overriding by variation params is built in the RequestThrottler :) This is just
the default quota value if no variation param is given.

[Marc Treib, 2016/07/25 10:11:55]

I see... this is surprising to me. Since everything else related to the quota is
defined in the RequestThrottler, should we maybe move the default quota
definition there too?
If not, please at least add a "Default" somewhere in the name, to make it clear
to the reader that it might be overridden.

[jkrcal, 2016/07/25 10:26:59]

Makes sense. Done.

+
 std::string FetchResultToString(NTPSnippetsFetcher::FetchResult result) {
   switch (result) {
     case NTPSnippetsFetcher::FetchResult::SUCCESS:
@@ -158,6 +160,7 @@ NTPSnippetsFetcher::NTPSnippetsFetcher(
     SigninManagerBase* signin_manager,
     OAuth2TokenService* token_service,
     scoped_refptr<URLRequestContextGetter> url_request_context_getter,
+    PrefService* pref_service,
     const ParseJSONCallback& parse_json_callback,
     bool is_stable_channel)
     : OAuth2TokenService::Consumer("ntp_snippets"),
@@ -172,6 +175,10 @@ NTPSnippetsFetcher::NTPSnippetsFetcher(
                      : CHROME_READER_API),
       is_stable_channel_(is_stable_channel),
       tick_clock_(new base::DefaultTickClock()),
+      request_throttler_(
+          pref_service,
+          RequestThrottler::RequestType::CONTENT_SUGGESTION_FETCHER,
+          kArticlesQuotaPerDay),
       weak_ptr_factory_(this) {
   // Parse the variation parameters and set the defaults if missing.
   std::string personalization = variations::GetVariationParamValue(
@@ -214,7 +221,11 @@ void NTPSnippetsFetcher::SetCallback(
 void NTPSnippetsFetcher::FetchSnippetsFromHosts(
     const std::set<std::string>& hosts,
     const std::string& language_code,
-    int count) {
+    int count,
+    bool force_request) {
+  if (!request_throttler_.DemandQuotaForRequest(force_request))
+    return;
+
   hosts_ = hosts;
   fetch_start_time_ = tick_clock_->NowTicks();