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 1013 matching lines @@
 
 #if defined(OS_ANDROID)
 const FeatureEntry::FeatureParam kPersistentMenuItemEnabled[] = {
     {"persistent_menu_item_enabled", "true"}};
 
 const FeatureEntry::FeatureVariation kDataReductionMainMenuFeatureVariations[] =
     {{"(persistent)", kPersistentMenuItemEnabled,
       arraysize(kPersistentMenuItemEnabled), nullptr}};
 #endif  // OS_ANDROID
 
+const FeatureEntry::FeatureParam kStalePreviewsTimestampParams[] = {
+    {"min_staleness_in_minutes", "2"},
+    {"max_staleness_in_minutes", "1440"}};
+
+const FeatureEntry::FeatureVariation
+    kStalePreviewsTimestampFeatureVariations[] = {
+        {"(with staleness params)", kStalePreviewsTimestampParams,
+         arraysize(kStalePreviewsTimestampParams), nullptr}};
+
 const FeatureEntry::Choice kEnableHeapProfilingChoices[] = {
     {flags_ui::kGenericExperimentChoiceDisabled, "", ""},
     {flag_descriptions::kEnableHeapProfilingModePseudo,
      switches::kEnableHeapProfiling, switches::kEnableHeapProfilingModePseudo},
     {flag_descriptions::kEnableHeapProfilingModeNative,
      switches::kEnableHeapProfiling, switches::kEnableHeapProfilingModeNative},
     {flag_descriptions::kEnableHeapProfilingTaskProfiler,
      switches::kEnableHeapProfiling,
      switches::kEnableHeapProfilingTaskProfiler}};
 
@@ skipping 905 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_WITH_PARAMS_VALUE_TYPE(previews::features::kStalePreviewsTimestamp,

[megjablon, 2017/06/21 00:25:07]

Is there any way to add the params for a feature under the Enabled group? It
doesn't make sense for us to have an Enabled group without the params in this
case.

[Alexei Svitkine (slow), 2017/06/22 16:29:21]

Can you simply specify default values for params in the code where you're
querying them?

[megjablon, 2017/06/22 20:43:22]

Done.

+                                    kStalePreviewsTimestampFeatureVariations,
+                                    "StalePreviewsTimestamp")},
     {"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 1344 matching lines @@
 const base::HistogramBase::Sample kBadSwitchFormatHistogramId = 0;
 
 const FeatureEntry* GetFeatureEntries(size_t* count) {
   *count = arraysize(kFeatureEntries);
   return kFeatureEntries;
 }
 
 }  // namespace testing
 
 }  // namespace about_flags