Do nothing on OnSessionStopped if ARC is being restarted.

components/arc/arc_session_observer.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/arc/arc_session_observer.h"
-
-namespace arc {
-
-std::ostream& operator<<(std::ostream& os,
-                         ArcSessionObserver::StopReason reason) {
-  switch (reason) {
-#define CASE_IMPL(val)                      \
-  case ArcSessionObserver::StopReason::val: \
-    return os << #val
-
-    CASE_IMPL(SHUTDOWN);
-    CASE_IMPL(GENERIC_BOOT_FAILURE);
-    CASE_IMPL(LOW_DISK_SPACE);
-    CASE_IMPL(CRASH);
-#undef CASE_IMPL
-  }
-
-  // In case of unexpected value, output the int value.
-  return os << "StopReason(" << static_cast<int>(reason) << ")";
-}
-
-}  // namespace arc