Simplify Instant field trials.

Simplifies the field trials by removing the unnecessary a/b split. Also:
+ Updates 'ix' param codes and group percentages.
+ Removes UMA restriction, but this is a no-op at the moment, since it's
  handled on the server side.

BUG=none
TEST=none (no change in functionality or UI).


Review URL: http://codereview.chromium.org/9797003

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@128098 0039d316-1c4b-4281-b951-d872f2087c98

4 files changed, 85 insertions, 181 deletions

diff --git a/chrome/browser/instant/instant_field_trial.cc b/chrome/browser/instant/instant_field_trial.cc
index 48a562e..dee598f 100644
--- a/chrome/browser/instant/instant_field_trial.cc
+++ b/chrome/browser/instant/instant_field_trial.cc
@@ -17,52 +17,28 @@ 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_instant_experiment_a = 0;
-int g_instant_experiment_b = 0;
-
-int g_hidden_experiment_a = 0;
-int g_hidden_experiment_b = 0;
-
-int g_silent_experiment_a = 0;
-int g_silent_experiment_b = 0;
-
-int g_suggest_experiment_a = 0;
-int g_suggest_experiment_b = 0;
-
-int g_uma_control_a = 0;
-int g_uma_control_b = 0;
-
-int g_all_control_a = 0;
-int g_all_control_b = 0;
+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", 2012, 7, 1));
+      new base::FieldTrial("Instant", 1000, "Inactive", 2013, 7, 1));
 
   // Try to give the user a consistent experience, if possible.
   if (base::FieldTrialList::IsOneTimeRandomizationEnabled())
     trial->UseOneTimeRandomization();
 
-  g_instant_experiment_a = trial->AppendGroup("InstantExperimentA", 50);
-  g_instant_experiment_b = trial->AppendGroup("InstantExperimentB", 50);
-
-  g_hidden_experiment_a = trial->AppendGroup("HiddenExperimentA", 50);
-  g_hidden_experiment_b = trial->AppendGroup("HiddenExperimentB", 50);
-
-  g_silent_experiment_a = trial->AppendGroup("SilentExperimentA", 50);
-  g_silent_experiment_b = trial->AppendGroup("SilentExperimentB", 50);
-
-  g_suggest_experiment_a = trial->AppendGroup("SuggestExperimentA", 50);
-  g_suggest_experiment_b = trial->AppendGroup("SuggestExperimentB", 50);
-
-  g_uma_control_a = trial->AppendGroup("UmaControlA", 50);
-  g_uma_control_b = trial->AppendGroup("UmaControlB", 50);
-
-  g_all_control_a = trial->AppendGroup("AllControlA", 50);
-  g_all_control_b = trial->AppendGroup("AllControlB", 50);
+  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%
 }
 
 // static
@@ -72,15 +48,16 @@ InstantFieldTrial::Group InstantFieldTrial::GetGroup(Profile* profile) {
     std::string switch_value =
         command_line->GetSwitchValueASCII(switches::kInstantFieldTrial);
     if (switch_value == switches::kInstantFieldTrialInstant)
-      return INSTANT_EXPERIMENT_A;
-    else if (switch_value == switches::kInstantFieldTrialHidden)
-      return HIDDEN_EXPERIMENT_A;
-    else if (switch_value == switches::kInstantFieldTrialSilent)
-      return SILENT_EXPERIMENT_A;
-    else if (switch_value == switches::kInstantFieldTrialSuggest)
-      return SUGGEST_EXPERIMENT_A;
-    else
-      return INACTIVE;
+      return INSTANT;
+    if (switch_value == switches::kInstantFieldTrialSuggest)
+      return SUGGEST;
+    if (switch_value == switches::kInstantFieldTrialHidden)
+      return HIDDEN;
+    if (switch_value == switches::kInstantFieldTrialSilent)
+      return SILENT;
+    if (switch_value == switches::kInstantFieldTrialControl)
+      return CONTROL;
+    return INACTIVE;
   }
 
   const int group = base::FieldTrialList::FindValue("Instant");
@@ -90,49 +67,23 @@ InstantFieldTrial::Group InstantFieldTrial::GetGroup(Profile* profile) {
   }
 
   const PrefService* prefs = profile ? profile->GetPrefs() : NULL;
-  if (!prefs ||
+  if (!prefs || profile->IsOffTheRecord() ||
       prefs->GetBoolean(prefs::kInstantEnabledOnce) ||
+      !prefs->GetBoolean(prefs::kSearchSuggestEnabled) ||
       prefs->IsManagedPreference(prefs::kInstantEnabled)) {
     return INACTIVE;
   }
 
-  // First, deal with the groups that don't require UMA opt-in.
-  if (group == g_silent_experiment_a)
-    return SILENT_EXPERIMENT_A;
-  if (group == g_silent_experiment_b)
-    return SILENT_EXPERIMENT_B;
-
-  if (group == g_all_control_a)
-    return ALL_CONTROL_A;
-  if (group == g_all_control_b)
-    return ALL_CONTROL_B;
-
-  // All other groups require UMA and suggest, else bounce back to INACTIVE.
-  if (profile->IsOffTheRecord() ||
-      !MetricsServiceHelper::IsMetricsReportingEnabled() ||
-      !prefs->GetBoolean(prefs::kSearchSuggestEnabled)) {
-    return INACTIVE;
-  }
-
-  if (group == g_instant_experiment_a)
-    return INSTANT_EXPERIMENT_A;
-  if (group == g_instant_experiment_b)
-    return INSTANT_EXPERIMENT_B;
-
-  if (group == g_hidden_experiment_a)
-    return HIDDEN_EXPERIMENT_A;
-  if (group == g_hidden_experiment_b)
-    return HIDDEN_EXPERIMENT_B;
-
-  if (group == g_suggest_experiment_a)
-    return SUGGEST_EXPERIMENT_A;
-  if (group == g_suggest_experiment_b)
-    return SUGGEST_EXPERIMENT_B;
-
-  if (group == g_uma_control_a)
-    return UMA_CONTROL_A;
-  if (group == g_uma_control_b)
-    return UMA_CONTROL_B;
+  if (group == g_instant)
+    return INSTANT;
+  if (group == g_suggest)
+    return SUGGEST;
+  if (group == g_hidden)
+    return HIDDEN;
+  if (group == g_silent)
+    return SILENT;
+  if (group == g_control)
+    return CONTROL;
 
   NOTREACHED();
   return INACTIVE;
@@ -141,48 +92,31 @@ InstantFieldTrial::Group InstantFieldTrial::GetGroup(Profile* profile) {
 // static
 bool InstantFieldTrial::IsInstantExperiment(Profile* profile) {
   Group group = GetGroup(profile);
-  return group == INSTANT_EXPERIMENT_A || group == INSTANT_EXPERIMENT_B ||
-         group == HIDDEN_EXPERIMENT_A || group == HIDDEN_EXPERIMENT_B ||
-         group == SILENT_EXPERIMENT_A || group == SILENT_EXPERIMENT_B ||
-         group == SUGGEST_EXPERIMENT_A || group == SUGGEST_EXPERIMENT_B;
+  return group == INSTANT || group == SUGGEST || group == HIDDEN ||
+         group == SILENT;
 }
 
 // static
 bool InstantFieldTrial::IsHiddenExperiment(Profile* profile) {
   Group group = GetGroup(profile);
-  return group == HIDDEN_EXPERIMENT_A || group == HIDDEN_EXPERIMENT_B ||
-         group == SILENT_EXPERIMENT_A || group == SILENT_EXPERIMENT_B ||
-         group == SUGGEST_EXPERIMENT_A || group == SUGGEST_EXPERIMENT_B;
+  return group == SUGGEST || group == HIDDEN || group == SILENT;
 }
 
 // static
 bool InstantFieldTrial::IsSilentExperiment(Profile* profile) {
   Group group = GetGroup(profile);
-  return group == SILENT_EXPERIMENT_A || group == SILENT_EXPERIMENT_B;
+  return group == SILENT;
 }
 
 // static
 std::string InstantFieldTrial::GetGroupName(Profile* profile) {
   switch (GetGroup(profile)) {
     case INACTIVE: return std::string();
-
-    case INSTANT_EXPERIMENT_A: return "_InstantExperimentA";
-    case INSTANT_EXPERIMENT_B: return "_InstantExperimentB";
-
-    case HIDDEN_EXPERIMENT_A: return "_HiddenExperimentA";
-    case HIDDEN_EXPERIMENT_B: return "_HiddenExperimentB";
-
-    case SILENT_EXPERIMENT_A: return "_SilentExperimentA";
-    case SILENT_EXPERIMENT_B: return "_SilentExperimentB";
-
-    case SUGGEST_EXPERIMENT_A: return "_SuggestExperimentA";
-    case SUGGEST_EXPERIMENT_B: return "_SuggestExperimentB";
-
-    case UMA_CONTROL_A: return "_UmaControlA";
-    case UMA_CONTROL_B: return "_UmaControlB";
-
-    case ALL_CONTROL_A: return "_AllControlA";
-    case ALL_CONTROL_B: return "_AllControlB";
+    case INSTANT:  return "_Instant";
+    case SUGGEST:  return "_Suggest";
+    case HIDDEN:   return "_Hidden";
+    case SILENT:   return "_Silent";
+    case CONTROL:  return "_Control";
   }
 
   NOTREACHED();
@@ -191,26 +125,19 @@ std::string InstantFieldTrial::GetGroupName(Profile* profile) {
 
 // static
 std::string InstantFieldTrial::GetGroupAsUrlParam(Profile* profile) {
+  bool uma = MetricsServiceHelper::IsMetricsReportingEnabled();
   switch (GetGroup(profile)) {
     case INACTIVE: return std::string();
-
-    case INSTANT_EXPERIMENT_A: return "ix=iea&";
-    case INSTANT_EXPERIMENT_B: return "ix=ieb&";
-
-    case HIDDEN_EXPERIMENT_A: return "ix=hea&";
-    case HIDDEN_EXPERIMENT_B: return "ix=heb&";
-
-    case SILENT_EXPERIMENT_A: return "ix=sea&";
-    case SILENT_EXPERIMENT_B: return "ix=seb&";
-
-    case SUGGEST_EXPERIMENT_A: return "ix=tea&";
-    case SUGGEST_EXPERIMENT_B: return "ix=teb&";
-
-    case UMA_CONTROL_A: return "ix=uca&";
-    case UMA_CONTROL_B: return "ix=ucb&";
-
-    case ALL_CONTROL_A: return "ix=aca&";
-    case ALL_CONTROL_B: return "ix=acb&";
+    case INSTANT: if (uma) return "ix=ui&";
+                           return "ix=ni&";
+    case SUGGEST: if (uma) return "ix=ut&";
+                           return "ix=nt&";
+    case HIDDEN:  if (uma) return "ix=uh&";
+                           return "ix=nh&";
+    case SILENT:  if (uma) return "ix=us&";
+                           return "ix=ns&";
+    case CONTROL: if (uma) return "ix=uc&";
+                           return "ix=nc&";
   }
 
   NOTREACHED();
@@ -220,6 +147,5 @@ std::string InstantFieldTrial::GetGroupAsUrlParam(Profile* profile) {
 // static
 bool InstantFieldTrial::ShouldSetSuggestedText(Profile* profile) {
   Group group = GetGroup(profile);
-  return !(group == HIDDEN_EXPERIMENT_A || group == HIDDEN_EXPERIMENT_B ||
-           group == SILENT_EXPERIMENT_A || group == SILENT_EXPERIMENT_B);
+  return group != HIDDEN && group != SILENT;
 }
diff --git a/chrome/browser/instant/instant_field_trial.h b/chrome/browser/instant/instant_field_trial.h
index 5e2b3f8..a6f390d 100644
--- a/chrome/browser/instant/instant_field_trial.h
+++ b/chrome/browser/instant/instant_field_trial.h
@@ -1,4 +1,4 @@
-// Copyright (c) 2011 The Chromium Authors. All rights reserved.
+// 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.
 
@@ -19,57 +19,32 @@ class Profile;
 // Instant preference is respected. Incognito profiles are also INACTIVE.
 //
 // The following mutually exclusive groups each select a small random sample of
-// the remaining users. Instant is enabled with preloading for the EXPERIMENT
-// groups. It remains disabled, as is default, for the CONTROL groups.
+// the remaining users. Instant is enabled with preloading of the search engine
+// homepage for all the experiment groups. It remains disabled, as is default,
+// for the CONTROL group.
 //
-// INSTANT_EXPERIMENT: Queries are issued as the user types, and previews are
-//     shown. If the user hasn't opted to send metrics (UMA) data, they are
-//     bounced back to INACTIVE.
+// INSTANT: Queries are issued as the user types. Predicted query is inline
+//     autocompleted into the omnibox. Result previews are shown.
 //
-// HIDDEN_EXPERIMENT: Queries are issued as the user types, but no preview is
-//     shown until they press <Enter>. If the user hasn't opted to send metrics
-//     (UMA) data, they are bounced back to INACTIVE. Suggestions obtained from
-//     Instant are not propagated back to the omnibox.
+// SUGGEST: Same as INSTANT, without the previews.
 //
-// SILENT_EXPERIMENT: No queries are issued until the user presses <Enter>. No
-//     previews are shown. The user is not required to send metrics (UMA) data.
+// HIDDEN: Same as SUGGEST, without the inline autocompletion.
 //
-// SUGGEST_EXPERIMENT: Same as HIDDEN, except that the Instant suggestions are
-//     autocompleted inline into the omnibox.
+// SILENT: Same as HIDDEN, without issuing queries as the user types. The query
+//     is sent only after the user presses <Enter>.
 //
-// UMA_CONTROL: Instant is disabled. If the user hasn't opted to send metrics
-//     (UMA) data, they are bounced back to INACTIVE.
-//
-// ALL_CONTROL: Instant is disabled. The user is not required to send metrics
-//     (UMA) data.
+// CONTROL: Instant is disabled.
 //
 // Users not chosen into any of the above groups are INACTIVE.
-//
-// Each non-INACTIVE group is split into two equal subgroups, to detect bias
-// between them when analyzing metrics. The subgroups are denoted by "_A" and
-// "_B" suffixes, and are treated identically for all other purposes.
 class InstantFieldTrial {
  public:
   enum Group {
     INACTIVE,
-
-    INSTANT_EXPERIMENT_A,
-    INSTANT_EXPERIMENT_B,
-
-    HIDDEN_EXPERIMENT_A,
-    HIDDEN_EXPERIMENT_B,
-
-    SILENT_EXPERIMENT_A,
-    SILENT_EXPERIMENT_B,
-
-    SUGGEST_EXPERIMENT_A,
-    SUGGEST_EXPERIMENT_B,
-
-    UMA_CONTROL_A,
-    UMA_CONTROL_B,
-
-    ALL_CONTROL_A,
-    ALL_CONTROL_B,
+    INSTANT,
+    SUGGEST,
+    HIDDEN,
+    SILENT,
+    CONTROL
   };
 
   // Activate the field trial. Before this call, all calls to GetGroup will
@@ -79,25 +54,25 @@ class InstantFieldTrial {
   // Return the field trial group this profile belongs to.
   static Group GetGroup(Profile* profile);
 
-  // Check if the user is in any of the EXPERIMENT groups.
+  // Check if the user is in any of the experiment groups.
   static bool IsInstantExperiment(Profile* profile);
 
-  // Check if the user is in the HIDDEN, SILENT or SUGGEST EXPERIMENT groups.
+  // Check if the user is in the SUGGEST, HIDDEN or SILENT groups.
   static bool IsHiddenExperiment(Profile* profile);
 
-  // Check if the user is in the SILENT EXPERIMENT group.
+  // Check if the user is in the SILENT group.
   static bool IsSilentExperiment(Profile* profile);
 
   // Returns a string describing the user's group. Can be added to histogram
   // names, to split histograms by field trial groups.
   static std::string GetGroupName(Profile* profile);
 
- // Returns a string denoting the user's group, for adding as a URL param.
- static std::string GetGroupAsUrlParam(Profile* profile);
+  // Returns a string denoting the user's group, for adding as a URL param.
+  static std::string GetGroupAsUrlParam(Profile* profile);
 
- // Returns whether the Instant suggested text should be autocompleted inline
- // into the omnibox.
- static bool ShouldSetSuggestedText(Profile* profile);
+  // Returns whether the Instant suggested text should be autocompleted inline
+  // into the omnibox.
+  static bool ShouldSetSuggestedText(Profile* profile);
 
  private:
   DISALLOW_IMPLICIT_CONSTRUCTORS(InstantFieldTrial);
diff --git a/chrome/common/chrome_switches.cc b/chrome/common/chrome_switches.cc
index 3cd7ec4..0ad9771 100644
--- a/chrome/common/chrome_switches.cc
+++ b/chrome/common/chrome_switches.cc
@@ -747,13 +747,15 @@ const char kIncognito[]                     = "incognito";
 // Controls the Instant field trial. Valid values are defined below. If an
 // unknown value is supplied on the command line, the field trial is disabled.
 const char kInstantFieldTrial[]             = "instant-field-trial";
-// The field trial is forced into the HIDDEN_EXPERIMENT group.
+// The field trial is forced into the CONTROL group.
+const char kInstantFieldTrialControl[]      = "control";
+// The field trial is forced into the HIDDEN group.
 const char kInstantFieldTrialHidden[]       = "hidden";
-// The field trial is forced into the INSTANT_EXPERIMENT group.
+// The field trial is forced into the INSTANT group.
 const char kInstantFieldTrialInstant[]      = "instant";
-// The field trial is forced into the SILENT_EXPERIMENT group.
+// The field trial is forced into the SILENT group.
 const char kInstantFieldTrialSilent[]       = "silent";
-// The field trial is forced into the SUGGEST_EXPERIMENT group.
+// The field trial is forced into the SUGGEST group.
 const char kInstantFieldTrialSuggest[]      = "suggest";
 
 // URL to use for instant. If specified this overrides the url from the
diff --git a/chrome/common/chrome_switches.h b/chrome/common/chrome_switches.h
index 8d81db9..8bd0e001f 100644
--- a/chrome/common/chrome_switches.h
+++ b/chrome/common/chrome_switches.h
@@ -202,6 +202,7 @@ extern const char kImport[];
 extern const char kImportFromFile[];
 extern const char kIncognito[];
 extern const char kInstantFieldTrial[];
+extern const char kInstantFieldTrialControl[];
 extern const char kInstantFieldTrialHidden[];
 extern const char kInstantFieldTrialInstant[];
 extern const char kInstantFieldTrialSilent[];