[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 3271af1b496d68392bd0f1e0c7c648247462e920..baa2b99426338315ded31f1b8614eff85a08fa30 100644
--- a/components/ntp_snippets/ntp_snippets_service.cc
+++ b/components/ntp_snippets/ntp_snippets_service.cc
@@ -14,6 +14,11 @@
 
 namespace ntp_snippets {
 
+namespace {
+
+// TODO(treib): Add a command line param to control this.
+const int kDefaultFetchingIntervalSeconds = 30 * 60;

[Bernhard Bauer, 2016/02/16 16:19:08]

TBH, while we are testing this feature, I would reduce the interval even more,
maybe to 5 minutes, but for production 30 minutes seems very frequently (keep in
mind this unconditionally starts the whole browser process every thirty
minutes).

Longer term, it would be cool to e.g. be more aware of if the browser process is
already running, or to integrate more with history analysis to anticipate times
when the user is likely to actually look at snippets.

[Marc Treib, 2016/02/16 16:54:27]

Eh, IMO the value doesn't really matter yet - I was assuming we'd have the
cmdline flag soon. But sure, reduced to 1 minute for now. (Why not go all the
way :) )
Yup. Something kinda sorta like that is on the roadmap.

+
 std::string ReadFileToString(const base::FilePath& path) {
   std::string data;
   bool success = base::ReadFileToString(path, &data);
@@ -21,13 +26,17 @@ 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(
@@ -37,6 +46,15 @@ NTPSnippetsService::NTPSnippetsService(
 
 NTPSnippetsService::~NTPSnippetsService() {}
 
+void NTPSnippetsService::Init(bool enabled) {
+  if (scheduler_) {

[Bernhard Bauer, 2016/02/16 16:19:08]

When would the scheduler be null?

[Marc Treib, 2016/02/16 16:54:27]

I was vaguely thinking of iOS, which has an NTPSnippetsServiceFactory
implementation (that I haven't updated yet) and not much else. Really no point
in that though - removed the null check.

+    if (enabled)
+      scheduler_->Schedule(kDefaultFetchingIntervalSeconds);
+    else
+      scheduler_->Unschedule();
+  }
+}
+
 void NTPSnippetsService::Shutdown() {
   FOR_EACH_OBSERVER(NTPSnippetsServiceObserver, observers_,
                     NTPSnippetsServiceShutdown(this));