AU: Simplify the automatic update check code a little.

Moves automatic update checks into the UpdateAttempter class.
This is in preparation for resolving 2394.

BUG=2394
TEST=unit tests, gmerged on device

Change-Id: I66ddf860cc7e19334187dc7f1892ead53fc936c6

Review URL: http://codereview.chromium.org/3167039
diff --git a/update_attempter.cc b/update_attempter.cc
index 7873166..b0c470b 100644
--- a/update_attempter.cc
+++ b/update_attempter.cc
@@ -35,6 +35,21 @@
 
 namespace chromeos_update_engine {
 
+namespace {
+
+const int kTimeoutOnce = 7 * 60;  // at 7 minutes
+const int kTimeoutPeriodic = 45 * 60;  // every 45 minutes
+const int kTimeoutFuzz = 10 * 60;  // +/- 5 minutes
+
+gboolean CheckForUpdatePeriodically(void* arg) {
+  UpdateAttempter* update_attempter = reinterpret_cast<UpdateAttempter*>(arg);
+  update_attempter->Update("", "");
+  update_attempter->SchedulePeriodicUpdateCheck(kTimeoutPeriodic);
+  return FALSE;  // Don't run again.
+}
+
+}  // namespace {}
+
 const char* kUpdateCompletedMarker = "/tmp/update_engine_autoupdate_completed";
 
 const char* UpdateStatusToString(UpdateStatus status) {
@@ -411,6 +426,27 @@
   return true;
 }
 
+void UpdateAttempter::InitiatePeriodicUpdateChecks() {
+  if (!utils::IsOfficialBuild()) {
+    LOG(WARNING) << "Non-official build: periodic update checks disabled.";
+    return;
+  }
+  if (utils::IsRemovableDevice(utils::RootDevice(utils::BootDevice()))) {
+    LOG(WARNING) << "Removable device boot: periodic update checks disabled.";
+    return;
+  }
+  // Kick off periodic update checks. The first check is scheduled
+  // |kTimeoutOnce| seconds from now. Subsequent checks are scheduled
+  // at |kTimeoutPeriodic|-second intervals.
+  SchedulePeriodicUpdateCheck(kTimeoutOnce);
+}
+
+void UpdateAttempter::SchedulePeriodicUpdateCheck(int seconds) {
+  seconds = utils::FuzzInt(seconds, kTimeoutFuzz);
+  g_timeout_add_seconds(seconds, CheckForUpdatePeriodically, this);
+  LOG(INFO) << "Next update check in " << seconds << " seconds.";
+}
+
 void UpdateAttempter::SetPriority(utils::ProcessPriority priority) {
   if (priority_ == priority) {
     return;