Supporting command line argument to force field trials

chrome/browser/instant/instant_field_trial.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/instant/instant_field_trial.h"
 
 #include "base/command_line.h"
 #include "base/metrics/field_trial.h"
 #include "chrome/browser/metrics/metrics_service.h"
 #include "chrome/browser/prefs/pref_service.h"
 #include "chrome/browser/profiles/profile.h"
 #include "chrome/common/chrome_switches.h"
 #include "chrome/common/pref_names.h"
 
 namespace {
 
 // Field trial IDs of the control and experiment groups. Though they are not
 // literally "const", they are set only once, in Activate() below. See the .h
 // file for what these groups represent.
+int g_inactive = -1;
 int g_instant = 0;
 int g_suggest = 0;
 int g_hidden  = 0;
 int g_silent  = 0;
 int g_control = 0;
 
 }
 
 // static
 void InstantFieldTrial::Activate() {
   scoped_refptr<base::FieldTrial> trial(
-      new base::FieldTrial("Instant", 1000, "Inactive", 2013, 7, 1));
+      base::FieldTrialList::FactoryGetFieldTrial(
+          "Instant", 1000, "Inactive", 2013, 7, 1, &g_inactive));
 
   // Try to give the user a consistent experience, if possible.
   if (base::FieldTrialList::IsOneTimeRandomizationEnabled())
     trial->UseOneTimeRandomization();
 
   g_instant = trial->AppendGroup("Instant",  10);  //  1%
   g_suggest = trial->AppendGroup("Suggest",  10);  //  1%
   g_hidden  = trial->AppendGroup("Hidden",  960);  // 96%
   g_silent  = trial->AppendGroup("Silent",   10);  //  1%
   g_control = trial->AppendGroup("Control",  10);  //  1%
@@ skipping 27 matching lines @@
       group = HIDDEN;
     else if (switch_value == switches::kInstantFieldTrialSilent)
       group = SILENT;
     else if (switch_value == switches::kInstantFieldTrialControl)
       group = CONTROL;
     UMA_HISTOGRAM_ENUMERATION("Instant.FieldTrial.Reason", 1, 10);
     return group;
   }
 
   const int group = base::FieldTrialList::FindValue("Instant");
-  if (group == base::FieldTrial::kNotFinalized ||
-      group == base::FieldTrial::kDefaultGroupNumber) {
+  if (group == base::FieldTrial::kNotFinalized || group == g_inactive) {
     UMA_HISTOGRAM_ENUMERATION("Instant.FieldTrial.Reason", 2, 10);
     return INACTIVE;
   }
 
   const PrefService* prefs = profile ? profile->GetPrefs() : NULL;
   if (!prefs) {
     UMA_HISTOGRAM_ENUMERATION("Instant.FieldTrial.Reason", 3, 10);
     return INACTIVE;
   }
 
@@ skipping 87 matching lines @@
 
   NOTREACHED();
   return std::string();
 }
 
 // static
 bool InstantFieldTrial::ShouldSetSuggestedText(Profile* profile) {
   Group group = GetGroup(profile);
   return group != HIDDEN && group != SILENT;
 }