sync: Implement per-type update processing

sync/engine/syncer.cc

Index: sync/engine/syncer.cc
diff --git a/sync/engine/syncer.cc b/sync/engine/syncer.cc
index 9f2c378b5cc42391d14b3c7f7a5f8be09758f227..50cc167bb968e8c85c38f2a344abd7cda98ec136 100644
--- a/sync/engine/syncer.cc
+++ b/sync/engine/syncer.cc
@@ -61,6 +61,7 @@ bool Syncer::NormalSyncShare(ModelTypeSet request_types,
   if (nudge_tracker.IsGetUpdatesRequired() ||
       session->context()->ShouldFetchUpdatesBeforeCommit()) {
     if (!DownloadAndApplyUpdates(
+            request_types,
             session,
             base::Bind(&BuildNormalDownloadUpdates,
                        session,
@@ -85,6 +86,7 @@ bool Syncer::ConfigureSyncShare(
   HandleCycleBegin(session);
   VLOG(1) << "Configuring types " << ModelTypeSetToString(request_types);
   DownloadAndApplyUpdates(
+      request_types,
       session,
       base::Bind(&BuildDownloadUpdatesForConfigure,
                  session,
@@ -99,6 +101,7 @@ bool Syncer::PollSyncShare(ModelTypeSet request_types,
   HandleCycleBegin(session);
   VLOG(1) << "Polling types " << ModelTypeSetToString(request_types);
   DownloadAndApplyUpdates(
+      request_types,
       session,
       base::Bind(&BuildDownloadUpdatesForPoll,
                  session,
@@ -122,13 +125,15 @@ void Syncer::ApplyUpdates(SyncSession* session) {
 }
 
 bool Syncer::DownloadAndApplyUpdates(
+    ModelTypeSet request_types,
     SyncSession* session,
     base::Callback<void(sync_pb::ClientToServerMessage*)> build_fn) {
   while (!session->status_controller().ServerSaysNothingMoreToDownload()) {
     TRACE_EVENT0("sync", "DownloadUpdates");
     sync_pb::ClientToServerMessage msg;
     build_fn.Run(&msg);
-    SyncerError download_result = ExecuteDownloadUpdates(session, &msg);
+    SyncerError download_result =
+        ExecuteDownloadUpdates(request_types, session, &msg);
     session->mutable_status_controller()->set_last_download_updates_result(
         download_result);
     if (download_result != SYNCER_OK) {