sync: use progress markers instead of timestamps during GetUpdates

chrome/browser/sync/sessions/session_state.cc

Index: chrome/browser/sync/sessions/session_state.cc
diff --git a/chrome/browser/sync/sessions/session_state.cc b/chrome/browser/sync/sessions/session_state.cc
index 644d2f69cbc727089b19d828ce688544f13f0674..7e1cc948beed63d18d0bab383d48efcd76f9b71b 100644
--- a/chrome/browser/sync/sessions/session_state.cc
+++ b/chrome/browser/sync/sessions/session_state.cc
@@ -17,9 +17,9 @@ SyncSessionSnapshot::SyncSessionSnapshot(
     const SyncerStatus& syncer_status,
     const ErrorCounters& errors,
     int64 num_server_changes_remaining,
-    int64 max_local_timestamp,
     bool is_share_usable,
     const syncable::ModelTypeBitSet& initial_sync_ended,
+    std::string download_progress_markers[syncable::MODEL_TYPE_COUNT],
     bool more_to_sync,
     bool is_silenced,
     int64 unsynced_count,
@@ -28,14 +28,18 @@ SyncSessionSnapshot::SyncSessionSnapshot(
     : syncer_status(syncer_status),
       errors(errors),
       num_server_changes_remaining(num_server_changes_remaining),
-      max_local_timestamp(max_local_timestamp),
       is_share_usable(is_share_usable),
       initial_sync_ended(initial_sync_ended),
+      download_progress_markers(),
       has_more_to_sync(more_to_sync),
       is_silenced(is_silenced),
       unsynced_count(unsynced_count),
       num_conflicting_updates(num_conflicting_updates),
       did_commit_items(did_commit_items) {
+  for (int i = 0; i < syncable::MODEL_TYPE_COUNT; ++i) {
+    const_cast<std::string&>(this->download_progress_markers[i]).assign(
+        download_progress_markers[i]);
+  }
 }
 
 SyncSessionSnapshot::~SyncSessionSnapshot() {}
@@ -238,8 +242,7 @@ PerModelSafeGroupState::PerModelSafeGroupState(bool* dirty_flag)
 PerModelSafeGroupState::~PerModelSafeGroupState() {
 }
 
-PerModelTypeState::PerModelTypeState(bool* dirty_flag)
-    : current_download_timestamp(dirty_flag, 0) {
+PerModelTypeState::PerModelTypeState(bool* dirty_flag) {
 }
 
 PerModelTypeState::~PerModelTypeState() {