[NTP Snippets] Schedule periodic fetching

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 "base/files/file_path.h"
 #include "base/files/file_util.h"
 #include "base/json/json_string_value_serializer.h"
 #include "base/location.h"
 #include "base/path_service.h"
 #include "base/task_runner_util.h"
 #include "base/values.h"
 
 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);
   DLOG_IF(ERROR, !success) << "Error reading file " << path.LossyDisplayName();
   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(
       base::Bind(&NTPSnippetsService::OnSnippetsDownloaded,
                  weak_ptr_factory_.GetWeakPtr()));
 }
 
 NTPSnippetsService::~NTPSnippetsService() {}
 
+void NTPSnippetsService::Init(bool enabled) {
+  if (enabled)
+    scheduler_->Schedule(kDefaultFetchingIntervalSeconds);
+  else
+    scheduler_->Unschedule();
+}
+
 void NTPSnippetsService::Shutdown() {
   FOR_EACH_OBSERVER(NTPSnippetsServiceObserver, observers_,
                     NTPSnippetsServiceShutdown(this));
   loaded_ = false;
 }
 
 void NTPSnippetsService::FetchSnippets(bool overwrite) {
   snippets_fetcher_->FetchSnippets(overwrite);
 }
 
@@ skipping 53 matching lines @@
 void NTPSnippetsService::OnSnippetsDownloaded(
     const base::FilePath& download_path) {
   base::PostTaskAndReplyWithResult(
       file_task_runner_.get(), FROM_HERE,
       base::Bind(&ReadFileToString, download_path),
       base::Bind(&NTPSnippetsService::OnFileReadDone,
                  weak_ptr_factory_.GetWeakPtr()));
 }
 
 }  // namespace ntp_snippets