[Sync] Move //sync to //components/sync.

sync/engine/nudge_source.cc

-// Copyright (c) 2012 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 "sync/engine/nudge_source.h"
-
-#include "base/logging.h"
-
-namespace syncer {
-
-#define ENUM_CASE(x) case x: return #x; break
-
-const char* GetNudgeSourceString(NudgeSource nudge_source) {
-  switch (nudge_source) {
-    ENUM_CASE(NUDGE_SOURCE_UNKNOWN);
-    ENUM_CASE(NUDGE_SOURCE_NOTIFICATION);
-    ENUM_CASE(NUDGE_SOURCE_LOCAL);
-    ENUM_CASE(NUDGE_SOURCE_LOCAL_REFRESH);
-  }
-  NOTREACHED();
-  return "";
-}
-
-#undef ENUM_CASE
-
-}  // namespace syncer