Fix PrerenderFromOmnibox field trial by removing the hard-coded percentages,

chrome/browser/prerender/prerender_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/prerender/prerender_field_trial.h"
 
 #include "base/command_line.h"
 #include "base/logging.h"
 #include "base/metrics/field_trial.h"
 #include "base/metrics/histogram.h"
@@ skipping 15 matching lines @@
 using base::FieldTrial;
 using base::FieldTrialList;
 using base::StringToInt;
 using std::string;
 using std::vector;
 
 namespace prerender {
 
 namespace {
 
-const char kOmniboxTrialName[] = "PrerenderFromOmnibox";
-int g_omnibox_trial_default_group_number = kint32min;
-
 const char kDisabledGroup[] = "Disabled";
 const char kEnabledGroup[] = "Enabled";
 
 const char kLocalPredictorSpecTrialName[] = "PrerenderLocalPredictorSpec";
 const char kLocalPredictorKeyName[] = "LocalPredictor";
 const char kLocalPredictorUnencryptedSyncOnlyKeyName[] =
     "LocalPredictorUnencryptedSyncOnly";
 const char kLocalPredictorNetworkPredictionEnabledOnly[] =
     "LocalPredictorNetworkPredictionEnabledOnly";
 const char kLocalPredictorOnCellularOnly[] = "LocalPredictorOnCellularOnly";
@@ skipping 145 matching lines @@
   } else if (trial_group == experiment_match_complete_group) {
     PrerenderManager::SetMode(
         PrerenderManager::PRERENDER_MODE_EXPERIMENT_MATCH_COMPLETE_GROUP);
   } else {
     NOTREACHED();
   }
 }
 
 }  // end namespace
 
-void ConfigureOmniboxPrerender();
-
 void ConfigurePrerender(const CommandLine& command_line) {
   enum PrerenderOption {
     PRERENDER_OPTION_AUTO,
     PRERENDER_OPTION_DISABLED,
     PRERENDER_OPTION_ENABLED,
   };
 
   PrerenderOption prerender_option = PRERENDER_OPTION_AUTO;
   if (command_line.HasSwitch(switches::kPrerenderMode)) {
     const string switch_value =
@@ skipping 22 matching lines @@
       break;
     case PRERENDER_OPTION_DISABLED:
       PrerenderManager::SetMode(PrerenderManager::PRERENDER_MODE_DISABLED);
       break;
     case PRERENDER_OPTION_ENABLED:
       PrerenderManager::SetMode(PrerenderManager::PRERENDER_MODE_ENABLED);
       break;
     default:
       NOTREACHED();
   }
-
-  ConfigureOmniboxPrerender();
-}
-
-void ConfigureOmniboxPrerender() {
-  // Field trial to see if we're enabled.
-  const FieldTrial::Probability kDivisor = 100;
-
-  FieldTrial::Probability kDisabledProbability = 10;
-  chrome::VersionInfo::Channel channel = chrome::VersionInfo::GetChannel();
-  if (channel == chrome::VersionInfo::CHANNEL_STABLE ||
-      channel == chrome::VersionInfo::CHANNEL_BETA) {
-    kDisabledProbability = 1;
-  }
-  scoped_refptr<FieldTrial> omnibox_prerender_trial(
-      FieldTrialList::FactoryGetFieldTrial(
-          kOmniboxTrialName, kDivisor, "OmniboxPrerenderEnabled",
-          2014, 12, 31, FieldTrial::SESSION_RANDOMIZED,
-          &g_omnibox_trial_default_group_number));
-  omnibox_prerender_trial->AppendGroup("OmniboxPrerenderDisabled",
-                                       kDisabledProbability);
 }
 
 bool IsOmniboxEnabled(Profile* profile) {
   if (!profile)
     return false;
 
   if (!PrerenderManager::IsPrerenderingPossible())
     return false;
 
   // Override any field trial groups if the user has set a command line flag.
   if (CommandLine::ForCurrentProcess()->HasSwitch(
       switches::kPrerenderFromOmnibox)) {
     const string switch_value =
         CommandLine::ForCurrentProcess()->GetSwitchValueASCII(
             switches::kPrerenderFromOmnibox);
 
     if (switch_value == switches::kPrerenderFromOmniboxSwitchValueEnabled)
       return true;
 
     if (switch_value == switches::kPrerenderFromOmniboxSwitchValueDisabled)
       return false;
 
     DCHECK_EQ(switches::kPrerenderFromOmniboxSwitchValueAuto, switch_value);
   }
 
-  const int group = FieldTrialList::FindValue(kOmniboxTrialName);
-  return group == FieldTrial::kNotFinalized ||
-         group == g_omnibox_trial_default_group_number;
+  return (FieldTrialList::FindFullName("PrerenderFromOmnibox") !=

[cbentzel, 2014/09/29 11:19:17]

Do you anticipate ever having multiple Disabled groups? Should this just check
if name begins with OmniboxPrerenderDisabled?

[tburkard, 2014/09/29 11:22:11]

I think we don't have a need for this at this point. All the other Finch trials
we have for prerender don't have this, so would make more sense to make such a
change in a way to cover all finch trials the same way. But like I said, I don't
see any specific need for this at this point.

Thanks.

+          "OmniboxPrerenderDisabled");
 }
 
 /*
 PrerenderLocalPredictorSpec is a field trial, and its value must have the
 following format:
 key1=value1:key2=value2:key3=value3
 eg "LocalPredictor=Enabled:SideEffectFreeWhitelist=Enabled"
 The function below extracts the value corresponding to a key provided from the
 LocalPredictorSpec.
 */
@@ skipping 206 matching lines @@
   return GetLocalPredictorSpecValue(kDisableSessionStorageNamespaceMerging) !=
       kDisabledGroup;
 }
 
 bool IsPrerenderCookieStoreEnabled() {
   return GetLocalPredictorSpecValue(kPrerenderCookieStore) != kDisabledGroup &&
       FieldTrialList::FindFullName(kPrerenderCookieStore) != kDisabledGroup;
 }
 
 }  // namespace prerender