Omnibox: Create HistoryQuickProvider new scoring field trial.

And add a beacon to the histograms to allow identification of users in it.

isherman: for field trial and histogram stuff (all files)
sky: for OWNERs approval history stuff

BUG=
TEST=by hand, changed probabilities of field trial, looked at omnibox behavior and histogram behavior


Review URL: https://chromiumcodereview.appspot.com/10532149

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@142451 0039d316-1c4b-4281-b951-d872f2087c98

4 files changed, 123 insertions, 14 deletions

diff --git a/chrome/browser/autocomplete/autocomplete_field_trial.cc b/chrome/browser/autocomplete/autocomplete_field_trial.cc
index 9f48b26..3f0f48a 100644
--- a/chrome/browser/autocomplete/autocomplete_field_trial.cc
+++ b/chrome/browser/autocomplete/autocomplete_field_trial.cc
@@ -17,6 +17,7 @@ namespace {
 static const char kDisallowInlineHQPFieldTrialName[] =
     "OmniboxDisallowInlineHQP";
 static const char kSuggestFieldTrialName[] = "OmniboxSearchSuggest";
+static const char kHQPNewScoringFieldTrialName[] = "OmniboxHQPNewScoring";
 
 // Field trial experiment probabilities.
 
@@ -31,6 +32,12 @@ const base::FieldTrial::Probability
 // will decide what behavior (if any) to change based on the group.
 const int kSuggestFieldTrialNumberOfGroups = 20;
 
+// For History Quick Provider new scoring field trial, put 25% ( = 25/100 )
+// of the users in the new scoring experiment group.
+const base::FieldTrial::Probability kHQPNewScoringFieldTrialDivisor = 100;
+const base::FieldTrial::Probability
+    kHQPNewScoringFieldTrialExperimentFraction = 25;
+
 // Field trial IDs.
 // Though they are not literally "const", they are set only once, in
 // Activate() below.
@@ -39,6 +46,9 @@ const int kSuggestFieldTrialNumberOfGroups = 20;
 // experiment group.
 int disallow_inline_hqp_experiment_group = 0;
 
+// Field trial ID for the History Quick Provider new scoring experiment group.
+int hqp_new_scoring_experiment_group = 0;
+
 }
 
 
@@ -90,6 +100,16 @@ void AutocompleteFieldTrial::Activate() {
         static_cast<chrome_variations::ID>(
             chrome_variations::kSuggestIDMin + i));
   }
+
+  // Create inline History Quick Provider new scoring field trial.
+  // Make it expire on January 14, 2013.
+  trial = base::FieldTrialList::FactoryGetFieldTrial(
+      kHQPNewScoringFieldTrialName, kHQPNewScoringFieldTrialDivisor,
+      "Standard", 2013, 1, 14, NULL);
+  if (base::FieldTrialList::IsOneTimeRandomizationEnabled())
+    trial->UseOneTimeRandomization();
+  hqp_new_scoring_experiment_group = trial->AppendGroup("NewScoring",
+      kHQPNewScoringFieldTrialExperimentFraction);
 }
 
 bool AutocompleteFieldTrial::InDisallowInlineHQPFieldTrial() {
@@ -130,3 +150,17 @@ int AutocompleteFieldTrial::GetSuggestGroupNameAsNumber() {
 int AutocompleteFieldTrial::GetSuggestNumberOfGroups() {
   return kSuggestFieldTrialNumberOfGroups;
 }
+
+bool AutocompleteFieldTrial::InHQPNewScoringFieldTrial() {
+  return base::FieldTrialList::TrialExists(kHQPNewScoringFieldTrialName);
+}
+
+bool AutocompleteFieldTrial::InHQPNewScoringFieldTrialExperimentGroup() {
+  if (!InHQPNewScoringFieldTrial())
+    return false;
+
+  // Return true if we're in the experiment group.
+  const int group = base::FieldTrialList::FindValue(
+      kHQPNewScoringFieldTrialName);
+  return group == hqp_new_scoring_experiment_group;
+}
diff --git a/chrome/browser/autocomplete/autocomplete_field_trial.h b/chrome/browser/autocomplete/autocomplete_field_trial.h
index 2b6b628..f179125 100644
--- a/chrome/browser/autocomplete/autocomplete_field_trial.h
+++ b/chrome/browser/autocomplete/autocomplete_field_trial.h
@@ -51,6 +51,21 @@ class AutocompleteFieldTrial {
   // to create.)
   static int GetSuggestNumberOfGroups();
 
+  // ---------------------------------------------------------
+  // For the History Quick Provider new scoring field trial.
+
+  // Returns whether the user is in any field trial group for this
+  // field trial.  False indicates that the field trial wasn't
+  // successfully created for some reason.
+  static bool InHQPNewScoringFieldTrial();
+
+  // Returns whether the user should get the experimental setup or
+  // the default setup for this field trial.  The experiment
+  // group uses "new scoring" (a complex multiplicative calculation
+  // that, among other differences from "old scoring", uses word
+  // break information).
+  static bool InHQPNewScoringFieldTrialExperimentGroup();
+
  private:
   DISALLOW_IMPLICIT_CONSTRUCTORS(AutocompleteFieldTrial);
 };
diff --git a/chrome/browser/history/scored_history_match.cc b/chrome/browser/history/scored_history_match.cc
index 4724f5a..724acbc 100644
--- a/chrome/browser/history/scored_history_match.cc
+++ b/chrome/browser/history/scored_history_match.cc
@@ -14,8 +14,10 @@
 
 #include "base/command_line.h"
 #include "base/i18n/case_conversion.h"
+#include "base/metrics/histogram.h"
 #include "base/string_util.h"
 #include "base/utf_string_conversions.h"
+#include "chrome/browser/autocomplete/autocomplete_field_trial.h"
 #include "chrome/browser/autocomplete/url_prefix.h"
 #include "chrome/common/chrome_switches.h"
 #include "content/public/browser/browser_thread.h"
@@ -35,18 +37,15 @@ const int kScoreRank[] = { 1450, 1200, 900, 400 };
 
 // ScoredHistoryMatch ----------------------------------------------------------
 
-bool ScoredHistoryMatch::initialized = false;
+bool ScoredHistoryMatch::initialized_ = false;
 bool ScoredHistoryMatch::use_new_scoring = false;
 
 ScoredHistoryMatch::ScoredHistoryMatch()
     : raw_score(0),
       can_inline(false) {
-  if (!initialized) {
-    const std::string switch_value = CommandLine::ForCurrentProcess()->
-        GetSwitchValueASCII(switches::kOmniboxHistoryQuickProviderNewScoring);
-    if (switch_value == switches::kOmniboxHistoryQuickProviderNewScoringEnabled)
-      use_new_scoring = true;
-    initialized = true;
+  if (!initialized_) {
+    InitializeNewScoringField();
+    initialized_ = true;
   }
 }
 
@@ -58,12 +57,9 @@ ScoredHistoryMatch::ScoredHistoryMatch(const URLRow& row,
     : HistoryMatch(row, 0, false, false),
       raw_score(0),
       can_inline(false) {
-  if (!initialized) {
-    const std::string switch_value = CommandLine::ForCurrentProcess()->
-        GetSwitchValueASCII(switches::kOmniboxHistoryQuickProviderNewScoring);
-    if (switch_value == switches::kOmniboxHistoryQuickProviderNewScoringEnabled)
-      use_new_scoring = true;
-    initialized = true;
+  if (!initialized_) {
+    InitializeNewScoringField();
+    initialized_ = true;
   }
 
   GURL gurl = row.url();
@@ -476,4 +472,64 @@ float ScoredHistoryMatch::GetPopularityScore(int typed_count,
       (5.0 + 3.0);
 }
 
+void ScoredHistoryMatch::InitializeNewScoringField() {
+  enum NewScoringOption {
+    OLD_SCORING = 0,
+    NEW_SCORING = 1,
+    NEW_SCORING_AUTO_BUT_NOT_IN_FIELD_TRIAL = 2,
+    NEW_SCORING_FIELD_TRIAL_DEFAULT_GROUP = 3,
+    NEW_SCORING_FIELD_TRIAL_EXPERIMENT_GROUP = 4,
+    NUM_OPTIONS = 5
+  };
+  // should always be overwritten
+  NewScoringOption new_scoring_option = NUM_OPTIONS;
+
+  const std::string switch_value = CommandLine::ForCurrentProcess()->
+      GetSwitchValueASCII(switches::kOmniboxHistoryQuickProviderNewScoring);
+  if (switch_value == switches::kOmniboxHistoryQuickProviderNewScoringEnabled) {
+    new_scoring_option = NEW_SCORING;
+    use_new_scoring = true;
+  } else if (switch_value ==
+             switches::kOmniboxHistoryQuickProviderNewScoringDisabled) {
+    new_scoring_option = OLD_SCORING;
+    use_new_scoring = false;
+  } else {
+    // We'll assume any other flag means automatic.
+    // Automatic means eligible for the field trial.
+
+    // For the field trial stuff to work correctly, we must be running
+    // on the same thread as the thread that created the field trial,
+    // which happens via a call to AutocompleteFieldTrial::Active in
+    // chrome_browser_main.cc on the main thread.  Let's check this to
+    // be sure.  We check "if we've heard of the UI thread then we'd better
+    // be on it."  The first part is necessary so unit tests pass.  (Many
+    // unit tests don't set up the threading naming system; hence
+    // CurrentlyOn(UI thread) will fail.)
+    DCHECK(!content::BrowserThread::IsWellKnownThread(
+               content::BrowserThread::UI) ||
+           content::BrowserThread::CurrentlyOn(content::BrowserThread::UI));
+    if (AutocompleteFieldTrial::InHQPNewScoringFieldTrial()) {
+      if (AutocompleteFieldTrial::
+          InHQPNewScoringFieldTrialExperimentGroup()) {
+        new_scoring_option = NEW_SCORING_FIELD_TRIAL_EXPERIMENT_GROUP;
+        use_new_scoring = true;
+      } else {
+        new_scoring_option = NEW_SCORING_FIELD_TRIAL_DEFAULT_GROUP;
+        use_new_scoring = false;
+      }
+    } else {
+      new_scoring_option = NEW_SCORING_AUTO_BUT_NOT_IN_FIELD_TRIAL;
+      use_new_scoring = false;
+    }
+  }
+
+  // Add a beacon to the logs that'll allow us to identify later what
+  // new scoring state a user is in.  Do this by incrementing a bucket in
+  // a histogram, where the bucket represents the user's new scoring state.
+  UMA_HISTOGRAM_ENUMERATION(
+      "Omnibox.HistoryQuickProviderNewScoringFieldTrialBeacon",
+      new_scoring_option, NUM_OPTIONS);
+
+}
+
 }  // namespace history
diff --git a/chrome/browser/history/scored_history_match.h b/chrome/browser/history/scored_history_match.h
index 2644014..4ddd73b 100644
--- a/chrome/browser/history/scored_history_match.h
+++ b/chrome/browser/history/scored_history_match.h
@@ -97,6 +97,10 @@ struct ScoredHistoryMatch : public history::HistoryMatch {
   static float GetPopularityScore(int typed_count,
                                   int visit_count);
 
+  // Sets use_new_scoring based on command line flags and/or
+  // field trial state.
+  static void InitializeNewScoringField();
+
   // End of functions used only in "new" scoring --------------------------
 
   // An interim score taking into consideration location and completeness
@@ -127,7 +131,7 @@ struct ScoredHistoryMatch : public history::HistoryMatch {
   static float* raw_term_score_to_topicality_score;
 
   // Allows us to determing setting for use_new_scoring_ only once.
-  static bool initialized;
+  static bool initialized_;
 
   // Whether to use new-score or old-scoring.  Set in the constructor
   // by examining command line flags.