Adding an Android about:flags feature for offline previews

components/previews/core/previews_experiments.cc

Index: components/previews/core/previews_experiments.cc
diff --git a/components/previews/core/previews_experiments.cc b/components/previews/core/previews_experiments.cc
index e8d738aa60a6b5fb0c735ab700faf301582065a2..87f3af14a01c716a740d5eed95d6cdef036fe30b 100644
--- a/components/previews/core/previews_experiments.cc
+++ b/components/previews/core/previews_experiments.cc
@@ -6,11 +6,13 @@
 
 #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 {
 
@@ -136,10 +138,11 @@ net::EffectiveConnectionType EffectiveConnectionTypeThresholdForOffline() {
 
 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() &&

[tbansal1, 2017/05/03 17:35:19]

IIUC, this is not required anymore. Can we delete this?

[RyanSturm, 2017/05/03 21:26:25]

Not sure what you mean. I have to adjust the finch trials to have a seperate
case for "OfflinePreviews:enabled" and "OfflinePreviews:disabled"

[tbansal1, 2017/05/03 22:54:04]

Got it. In that case, should
IsIncludedInClientSidePreviewsExperimentsFieldTrial() also be returning true
when OfflinePreviews is enabled using AboutFlags. or, just make it private?

The comment for that method says:
// Returns true if any client-side previews experiment is active.

+          base::GetFieldTrialParamValue(kClientSidePreviewsFieldTrial,
+                                        kOfflinePagesSlowNetwork) ==
+              kExperimentEnabled);
 }
 
 int OfflinePreviewsVersion() {