Moves shared history test helpers into util classes.

components/omnibox/browser/in_memory_url_index_test_util.cc

+// Copyright 2016 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 "components/omnibox/browser/in_memory_url_index_test_util.h"
+
+#include "base/run_loop.h"
+#include "components/omnibox/browser/history_index_restore_observer.h"
+#include "components/omnibox/browser/in_memory_url_index.h"
+
+void BlockUntilInMemoryURLIndexIsRefreshed(InMemoryURLIndex* index) {
+  if (!index || index->restored())
+    return;
+  base::RunLoop run_loop;
+  HistoryIndexRestoreObserver observer(run_loop.QuitClosure());
+  index->set_restore_cache_observer(&observer);
+  run_loop.Run();
+  index->set_restore_cache_observer(nullptr);
+  DCHECK(index->restored());
+}