sync: Change progress marker checking in tests

chrome/browser/sync/test/integration/updated_progress_marker_checker.cc

+// Copyright 2014 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "chrome/browser/sync/test/integration/updated_progress_marker_checker.h"
+
+#include "chrome/browser/sync/profile_sync_service.h"
+#include "sync/internal_api/public/sessions/sync_session_snapshot.h"
+
+UpdatedProgressMarkerChecker::UpdatedProgressMarkerChecker(
+    ProfileSyncService* service) : SingleClientStatusChangeChecker(service) {}
+
+UpdatedProgressMarkerChecker::~UpdatedProgressMarkerChecker() {}
+
+bool UpdatedProgressMarkerChecker::IsExitConditionSatisfied() {
+  // Checks to see if our self-notify sync cycle has completed and
+  // there's nothing to commit.
+  //
+  // If we assume that no one else is committing at this time and that the
+  // current client did not commit anything in its previous sync cycle, then
+  // this client has the latest progress markers.
+  //
+  // The !service()->HasUnsyncedItems() check makes sure that we have nothing to
+  // commit.
+  //
+  // There is a subtle race condition here.  While committing items, the syncer
+  // will unset the IS_UNSYNCED bits in the directory.  However, the evidence of
+  // this current sync cycle won't be available from GetLastSessionSnapshot()
+  // until the sync cycle completes.  If we query this condition between the
+  // commit response processing and the end of the sync cycle, we could return a
+  // false positive.
+  //
+  // In practice, this doesn't happen very often because we only query the
+  // status when the waiting first starts and when we receive notification of a
+  // sync session complete or other significant event from the
+  // ProfileSyncService.  If we're calling this right after the sync session
+  // completes, then the snapshot is much more likely to be up to date.
+  const syncer::sessions::SyncSessionSnapshot& snap =
+      service()->GetLastSessionSnapshot();
+  return snap.model_neutral_state().num_successful_commits == 0 &&
+         !service()->HasUnsyncedItems();
+}
+
+std::string UpdatedProgressMarkerChecker::GetDebugMessage() const {
+  return "Waiting for progress markers";
+}