[NTP Snippets] Refresh the displayed snippets less frequently

components/ntp_snippets/ntp_snippets_service.cc

 // Copyright 2015 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/ntp_snippets_service.h"
 
 #include <algorithm>
 #include <utility>
 
 #include "base/command_line.h"
@@ skipping 221 matching lines @@
 }
 
 void NTPSnippetsService::ClearDiscardedSnippets() {
   discarded_snippets_.clear();
   StoreDiscardedSnippetsToPrefs();
   FetchSnippets();
 }
 
 void NTPSnippetsService::AddObserver(NTPSnippetsServiceObserver* observer) {
   observers_.AddObserver(observer);
-  observer->NTPSnippetsServiceLoaded();
 }
 
 void NTPSnippetsService::RemoveObserver(NTPSnippetsServiceObserver* observer) {
   observers_.RemoveObserver(observer);
 }
 
 void NTPSnippetsService::OnSuggestionsChanged(
     const SuggestionsProfile& suggestions) {
   std::set<std::string> hosts = GetSuggestionsHostsImpl(suggestions);
   if (hosts == GetSnippetHostsFromPrefs())
@@ skipping 171 matching lines @@
     if (snippet->expiry_date() < next_expiry)
       next_expiry = snippet->expiry_date();
   }
   DCHECK_GT(next_expiry, expiry);
   expiry_timer_.Start(FROM_HERE, next_expiry - expiry,
                       base::Bind(&NTPSnippetsService::RemoveExpiredSnippets,
                                  base::Unretained(this)));
 }
 
 }  // namespace ntp_snippets