Turn Popular sites on by default.

components/ntp_tiles/field_trial.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 "base/metrics/field_trial.h"
 
 #if defined(OS_ANDROID)
 #include <jni.h>
 #endif
 
@@ skipping 25 matching lines @@
 // On iOS it is not technically possible to prep the field trials on first
 // launch, the configuration file is downloaded too late. In order to run some
 // experiments that need to be active on first launch to be meaningful these
 // are hardcoded, but can be superceeded by a server side config on subsequent
 // launches.
 void SetUpFirstLaunchFieldTrial(bool is_stable_channel) {
   // Check first if a server side config superceeded this experiment.
   if (base::FieldTrialList::TrialExists(kPopularSitesFieldTrialName))
     return;
 
+  // The experiment is only for stable.

[sfiera, 2017/02/03 14:02:34]

I wouldn't describe this as an experiment anymore with 90% enabled. It looks
like you're keeping around a holdback so that you can continue to get metrics.
I'd describe it that way.

[noyau (Ping after 24h), 2017/02/21 12:24:16]

It's an experiment to keep 10% disabled :)

+  if (!is_stable_channel)

[rkaplow, 2017/02/07 03:56:46]

maybe also comment on intended behavior of other channels

[noyau (Ping after 24h), 2017/02/21 12:24:16]

Done.

+    return;
+
   // Stable channels will run with 10% probability.
-  // Non-stable channels will run with 50% probability.
   const base::FieldTrial::Probability kTotalProbability = 100;
-  const base::FieldTrial::Probability kEnabledAndControlProbability =
-      is_stable_channel ? 10 : 50;
+  const base::FieldTrial::Probability kEnabledAndControlProbability = 10;
 
-  // Experiment enabled until March 15, 2017. By default, disabled.
+  // Experiment enabled until April 26, 2017.
   scoped_refptr<base::FieldTrial> trial(
       base::FieldTrialList::FactoryGetFieldTrial(
           kPopularSitesFieldTrialName, kTotalProbability,
-          kPopularSiteDefaultGroup, 2017, 3, 15,  // Mar 15, 2017
+          kPopularSiteDefaultGroup, 2017, 4, 26,  // Apr 26, 2017
           base::FieldTrial::ONE_TIME_RANDOMIZED, nullptr));
 
   base::CommandLine* command_line = base::CommandLine::ForCurrentProcess();
   if (command_line->HasSwitch(ntp_tiles::switches::kEnableNTPPopularSites)) {
     trial->AppendGroup(kPopularSiteEnabledCommandLineSwitchGroup,
                        kTotalProbability);
   } else if (command_line->HasSwitch(
                  ntp_tiles::switches::kDisableNTPPopularSites)) {
     trial->AppendGroup(kPopularSiteDisabledCommandLineSwitchGroup,
                        kTotalProbability);
@@ skipping 22 matching lines @@
   if (cmd_line->HasSwitch(switches::kEnableNTPPopularSites))
     return true;
 
 #if defined(OS_ANDROID)
   if (Java_MostVisitedSites_isPopularSitesForceEnabled(
           base::android::AttachCurrentThread())) {
     return true;
   }
 #endif
 
-  return base::StartsWith(group_name, "Enabled",
+  // The experiment is enabled by default.

[sfiera, 2017/02/03 14:02:34]

This should be restricted to iOS.

[noyau (Ping after 24h), 2017/02/21 12:24:16]

Done.

But is this really true? Does that mean that Android is off by default? I
thought the feature was always turned on for Android?

[sfiera, 2017/02/21 13:10:21]

Nope. We still don't have launch approval for all countries.

+  return group_name.empty() || (group_name == kPopularSiteDefaultGroup) ||
+         base::StartsWith(group_name, "Enabled",
                           base::CompareCase::INSENSITIVE_ASCII);
 }
 
 }  // namespace ntp_tiles