[Sync] Refactoring polling to be reliable.

components/sync_driver/pref_names.cc

Index: components/sync_driver/pref_names.cc
diff --git a/components/sync_driver/pref_names.cc b/components/sync_driver/pref_names.cc
index b167a0b4165b3164a41e55edbde2a80cff0473d3..1a5727af138bd46c87fb71a6c080845fa7add18f 100644
--- a/components/sync_driver/pref_names.cc
+++ b/components/sync_driver/pref_names.cc
@@ -11,6 +11,9 @@ namespace prefs {
 // 64-bit integer serialization of the base::Time when the last sync occurred.
 const char kSyncLastSyncedTime[] = "sync.last_synced_time";
 
+// 64-bit integer serialization of the base::Time of the last sync poll.
+const char kSyncLastPollTime[] = "sync.last_poll_time";
+
 // Boolean specifying whether the user finished setting up sync.
 const char kSyncHasSetupCompleted[] = "sync.has_setup_completed";