[NTP Snippets] Schedule periodic fetching

components/ntp_snippets/ntp_snippets_service.cc

Index: components/ntp_snippets/ntp_snippets_service.cc
diff --git a/components/ntp_snippets/ntp_snippets_service.cc b/components/ntp_snippets/ntp_snippets_service.cc
index 66a923fe1e367cdc84df1e3f5a7338e637c392e3..db962648a7ac5bd1522e97dbd0ec5aa1da7bfa0d 100644
--- a/components/ntp_snippets/ntp_snippets_service.cc
+++ b/components/ntp_snippets/ntp_snippets_service.cc
@@ -14,6 +14,12 @@
 
 namespace ntp_snippets {
 
+namespace {
+
+// TODO(treib): This is an extremely small value, for ease of development.
+// Replace it by something sensible and add a command line param to control it.
+const int kDefaultFetchingIntervalSeconds = 60;
+
 std::string ReadFileToString(const base::FilePath& path) {
   std::string data;
   bool success = base::ReadFileToString(path, &data);
@@ -22,13 +28,17 @@ std::string ReadFileToString(const base::FilePath& path) {
   return data;
 }
 
+}  // namespace
+
 NTPSnippetsService::NTPSnippetsService(
     scoped_refptr<base::SequencedTaskRunner> file_task_runner,
     const std::string& application_language_code,
+    NTPSnippetsScheduler* scheduler,
     scoped_ptr<NTPSnippetsFetcher> snippets_fetcher)
     : loaded_(false),
       file_task_runner_(file_task_runner),
       application_language_code_(application_language_code),
+      scheduler_(scheduler),
       snippets_fetcher_(std::move(snippets_fetcher)),
       weak_ptr_factory_(this) {
   snippets_fetcher_callback_ = snippets_fetcher_->AddCallback(
@@ -38,6 +48,17 @@ NTPSnippetsService::NTPSnippetsService(
 
 NTPSnippetsService::~NTPSnippetsService() {}
 
+void NTPSnippetsService::Init(bool enabled) {
+  // The scheduler only exists on Android so far, it's null on other platforms.
+  if (!scheduler_)
+    return;
+
+  if (enabled)
+    scheduler_->Schedule(kDefaultFetchingIntervalSeconds);
+  else
+    scheduler_->Unschedule();
+}
+
 void NTPSnippetsService::Shutdown() {
   FOR_EACH_OBSERVER(NTPSnippetsServiceObserver, observers_,
                     NTPSnippetsServiceShutdown(this));