[Sync] Add support for server controlled nudge delays

sync/sessions/data_type_tracker.cc

Index: sync/sessions/data_type_tracker.cc
diff --git a/sync/sessions/data_type_tracker.cc b/sync/sessions/data_type_tracker.cc
index 12b53e9d03fd4b56d79577db35e2c15b7989e40b..da50bbfb4c5da3ba005ea8214aa7e2a0dcb908de 100644
--- a/sync/sessions/data_type_tracker.cc
+++ b/sync/sessions/data_type_tracker.cc
@@ -20,8 +20,9 @@ DataTypeTracker::DataTypeTracker()
 
 DataTypeTracker::~DataTypeTracker() { }
 
-void DataTypeTracker::RecordLocalChange() {
+base::TimeDelta DataTypeTracker::RecordLocalChange() {
   local_nudge_count_++;
+  return nudge_delay_;
 }
 
 void DataTypeTracker::RecordLocalRefreshRequest() {
@@ -218,5 +219,9 @@ void DataTypeTracker::UpdateThrottleState(base::TimeTicks now) {
   }
 }
 
+void DataTypeTracker::UpdateLocalNudgeDelay(base::TimeDelta delay) {
+  nudge_delay_ = delay;
+}
+
 }  // namespace sessions
 }  // namespace syncer