Introduce a request throttler for limiting requests in mobile NTP.

components/ntp_snippets/pref_names.cc

 // 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.
 
 #include "components/ntp_snippets/pref_names.h"
 
 namespace ntp_snippets {
 namespace prefs {
 
 const char kSnippetHosts[] = "ntp_snippets.hosts";
 
+const char kSnippetQuotaDayFormat[] = "ntp_snippets.quota.%s.day";
+const char kSnippetQuotaCountFormat[] = "ntp_snippets.quota.%s.count";

[Marc Treib, 2016/07/19 09:06:17]

Hmmm, this is very uncommon AFAIK. Do you have any precedent for generated pref
names?
If not, then I'd prefer a scheme where the client (i.e. NTPSnippetsFetcher)
registers the prefs itself, and passes the names to the RequestCounter.

[jkrcal, 2016/07/20 09:40:39]

Now, I register all of them in RequestCounter.

+
 }  // namespace prefs
 }  // namespace ntp_snippets