Add chrome://flag to enable the Stale Previews timestamp

chrome/browser/about_flags.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 "chrome/browser/about_flags.h"
 
 #include <iterator>
 #include <map>
 #include <set>
 #include <utility>
@@ skipping 1924 matching lines @@
 #endif  // OS_MACOSX
     {"data-reduction-proxy-lo-fi",
      flag_descriptions::kDataReductionProxyLoFiName,
      flag_descriptions::kDataReductionProxyLoFiDescription, kOsAll,
      MULTI_VALUE_TYPE(kDataReductionProxyLoFiChoices)},
     {"enable-data-reduction-proxy-lite-page",
      flag_descriptions::kEnableDataReductionProxyLitePageName,
      flag_descriptions::kEnableDataReductionProxyLitePageDescription, kOsAll,
      SINGLE_VALUE_TYPE(
          data_reduction_proxy::switches::kEnableDataReductionProxyLitePage)},
+    {"enable-stale-previews-timestamp",
+     flag_descriptions::kEnableStalePreviewsName,
+     flag_descriptions::kEnableStalePreviewsDescription, kOsAll,
+     FEATURE_VALUE_TYPE(previews::features::kStalePreviewsTimestamp)},
     {"enable-data-reduction-proxy-server-experiment",
      flag_descriptions::kEnableDataReductionProxyServerExperimentName,
      flag_descriptions::kEnableDataReductionProxyServerExperimentDescription,
      kOsAll, MULTI_VALUE_TYPE(kDataReductionProxyServerExperiment)},
 #if defined(OS_ANDROID)
     {"enable-data-reduction-proxy-savings-promo",
      flag_descriptions::kEnableDataReductionProxySavingsPromoName,
      flag_descriptions::kEnableDataReductionProxySavingsPromoDescription,
      kOsAndroid,
      SINGLE_VALUE_TYPE(data_reduction_proxy::switches::
@@ skipping 1354 matching lines @@
 const base::HistogramBase::Sample kBadSwitchFormatHistogramId = 0;
 
 const FeatureEntry* GetFeatureEntries(size_t* count) {
   *count = arraysize(kFeatureEntries);
   return kFeatureEntries;
 }
 
 }  // namespace testing
 
 }  // namespace about_flags