Adding an Android about:flags feature for offline previews

components/previews/core/previews_experiments.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/previews/core/previews_experiments.h"
 
 #include <string>
 
+#include "base/feature_list.h"
 #include "base/logging.h"
 #include "base/metrics/field_trial.h"
 #include "base/metrics/field_trial_params.h"
 #include "base/strings/string_number_conversions.h"
 #include "base/strings/string_util.h"
+#include "components/previews/core/previews_features.h"
 
 namespace previews {
 
 namespace {
 
 // The group of client-side previews experiments. Actually, this group is only
 // expected to control one PreviewsType (OFFLINE) as well as the blacklist.
 // Other PreviewsType's will be control by different field trial groups.
 const char kClientSidePreviewsFieldTrial[] = "ClientSidePreviews";
 
@@ skipping 44 matching lines @@
     const std::string& param_name,
     net::EffectiveConnectionType default_value) {
   net::EffectiveConnectionType value;
   if (!net::GetEffectiveConnectionTypeForName(
           base::GetFieldTrialParamValue(trial_name, param_name), &value)) {
     return default_value;
   }
   return value;
 }
 
+bool IsIncludedInClientSidePreviewsExperimentsFieldTrial() {
+  // By convention, an experiment in the client-side previews study enables use
+  // of at least one client-side previews optimization if its name begins with
+  // "Enabled."
+  return base::StartsWith(
+      base::FieldTrialList::FindFullName(kClientSidePreviewsFieldTrial),
+      kEnabled, base::CompareCase::SENSITIVE);
+}
+
 }  // namespace
 
 namespace params {
 
 size_t MaxStoredHistoryLengthForPerHostBlackList() {
   return GetParamValueAsSizeT(kClientSidePreviewsFieldTrial,
                               "per_host_max_stored_history_length", 4);
 }
 
 size_t MaxStoredHistoryLengthForHostIndifferentBlackList() {
@@ skipping 41 matching lines @@
 }
 
 net::EffectiveConnectionType EffectiveConnectionTypeThresholdForOffline() {
   return GetParamValueAsECT(kClientSidePreviewsFieldTrial,
                             kEffectiveConnectionTypeThreshold,
                             net::EFFECTIVE_CONNECTION_TYPE_SLOW_2G);
 }
 
 bool IsOfflinePreviewsEnabled() {
   //  Check if "show_offline_pages" is set to "true".
-  return IsIncludedInClientSidePreviewsExperimentsFieldTrial() &&
-         base::GetFieldTrialParamValue(kClientSidePreviewsFieldTrial,
-                                       kOfflinePagesSlowNetwork) ==
-             kExperimentEnabled;
+  return base::FeatureList::IsEnabled(features::kOfflinePreviews) ||
+         (IsIncludedInClientSidePreviewsExperimentsFieldTrial() &&
+          base::GetFieldTrialParamValue(kClientSidePreviewsFieldTrial,
+                                        kOfflinePagesSlowNetwork) ==
+              kExperimentEnabled);
 }
 
 int OfflinePreviewsVersion() {
   return GetParamValueAsInt(kClientSidePreviewsFieldTrial, kVersion, 0);
 }
 
 bool IsClientLoFiEnabled() {
   return base::StartsWith(
       base::FieldTrialList::FindFullName(kClientLoFiExperimentName), kEnabled,
       base::CompareCase::SENSITIVE);
 }
 
 int ClientLoFiVersion() {
   return GetParamValueAsInt(kClientLoFiExperimentName, kVersion, 0);
 }
 
 net::EffectiveConnectionType EffectiveConnectionTypeThresholdForClientLoFi() {
   return GetParamValueAsECT(kClientLoFiExperimentName,
                             kEffectiveConnectionTypeThreshold,
                             net::EFFECTIVE_CONNECTION_TYPE_2G);
 }
 
 }  // namespace params
 
-bool IsIncludedInClientSidePreviewsExperimentsFieldTrial() {
-  // By convention, an experiment in the client-side previews study enables use
-  // of at least one client-side previews optimization if its name begins with
-  // "Enabled."
-  return base::StartsWith(
-      base::FieldTrialList::FindFullName(kClientSidePreviewsFieldTrial),
-      kEnabled, base::CompareCase::SENSITIVE);
-}
-
 }  // namespace previews