Simulate transient error and verify exponential backoff.

chrome/browser/sync/engine/syncer.cc

Index: chrome/browser/sync/engine/syncer.cc
diff --git a/chrome/browser/sync/engine/syncer.cc b/chrome/browser/sync/engine/syncer.cc
index fae03fa1787d343373a5537f1a776b1352075129..49928598af092c0531b0de3add464b8a767b0463 100644
--- a/chrome/browser/sync/engine/syncer.cc
+++ b/chrome/browser/sync/engine/syncer.cc
@@ -112,6 +112,11 @@ void Syncer::SyncShare(sessions::SyncSession* session,
       }
       case DOWNLOAD_UPDATES: {
         VLOG(1) << "Downloading Updates";
+
+        // We would call set_syncing(false) at the SYNCER_END step. Note if
+        // we are on DOWNLOAD_UPDATES state we would not exit without
+        // going to SYNCER_END because of various cleanup steps.
+        session->status_controller()->set_syncing(true);
         DownloadUpdatesCommand download_updates;
         download_updates.Execute(session);
         next_step = PROCESS_CLIENT_COMMAND;
@@ -168,8 +173,6 @@ void Syncer::SyncShare(sessions::SyncSession* session,
       // These two steps are combined since they are executed within the same
       // write transaction.
       case BUILD_COMMIT_REQUEST: {
-        session->status_controller()->set_syncing(true);
-
         VLOG(1) << "Processing Commit Request";
         ScopedDirLookup dir(session->context()->directory_manager(),
                             session->context()->account_name());