Omnibox - Boost Frequency Scores Based on Number of Matching Pages

components/omnibox/browser/scored_history_match.cc

Index: components/omnibox/browser/scored_history_match.cc
diff --git a/components/omnibox/browser/scored_history_match.cc b/components/omnibox/browser/scored_history_match.cc
index bdde8e547430e18c6a9659cc48203cde566edf58..428989ce7d6a1f0008836c894d077df5db732e53 100644
--- a/components/omnibox/browser/scored_history_match.cc
+++ b/components/omnibox/browser/scored_history_match.cc
@@ -10,6 +10,7 @@
 #include <vector>
 
 #include "base/logging.h"
+#include "base/macros.h"
 #include "base/numerics/safe_conversions.h"
 #include "base/strings/string_number_conversions.h"
 #include "base/strings/string_split.h"
@@ -125,6 +126,10 @@ char ScoredHistoryMatch::hqp_relevance_buckets_str_[] =
 std::vector<ScoredHistoryMatch::ScoreMaxRelevance>*
     ScoredHistoryMatch::hqp_relevance_buckets_ = nullptr;
 
+OmniboxFieldTrial::NumMatchesScores*
+    ScoredHistoryMatch::num_matches_to_document_specificity_score_override_ =
+        nullptr;
+
 ScoredHistoryMatch::ScoredHistoryMatch()
     : ScoredHistoryMatch(history::URLRow(),
                          VisitInfoVector(),
@@ -133,8 +138,8 @@ ScoredHistoryMatch::ScoredHistoryMatch()
                          WordStarts(),
                          RowWordStarts(),
                          false,
-                         base::Time::Max()) {
-}
+                         1,
+                         base::Time::Max()) {}
 
 ScoredHistoryMatch::ScoredHistoryMatch(
     const history::URLRow& row,
@@ -144,6 +149,7 @@ ScoredHistoryMatch::ScoredHistoryMatch(
     const WordStarts& terms_to_word_starts_offsets,
     const RowWordStarts& word_starts,
     bool is_url_bookmarked,
+    size_t num_matching_pages,
     base::Time now)
     : HistoryMatch(row, 0, false, false), raw_score(0) {
   // NOTE: Call Init() before doing any validity checking to ensure that the
@@ -261,8 +267,11 @@ ScoredHistoryMatch::ScoredHistoryMatch(
   const float topicality_score = GetTopicalityScore(
       terms_vector.size(), url, terms_to_word_starts_offsets, word_starts);
   const float frequency_score = GetFrequency(now, is_url_bookmarked, visits);
-  raw_score = base::saturated_cast<int>(GetFinalRelevancyScore(
-      topicality_score, frequency_score, *hqp_relevance_buckets_));
+  const float specificity_score =
+      GetDocumentSpecificityScore(num_matching_pages);
+  raw_score = base::saturated_cast<int>(
+      GetFinalRelevancyScore(topicality_score, frequency_score,
+                             specificity_score, *hqp_relevance_buckets_));
 
   if (also_do_hup_like_scoring_ && likely_can_inline) {
     // HistoryURL-provider-like scoring gives any match that is
@@ -616,18 +625,43 @@ float ScoredHistoryMatch::GetFrequency(const base::Time& now,
          ScoredHistoryMatch::max_visits_to_score_;
 }
 
+float ScoredHistoryMatch::GetDocumentSpecificityScore(
+    size_t num_matching_pages) const {
+  // A mapping from the number of matching pages to their associated document
+  // specificity scores.  See omnibox_field_trial.h for more details.
+  CR_DEFINE_STATIC_LOCAL(OmniboxFieldTrial::NumMatchesScores,
+                         default_num_matches_to_document_specificity_score,
+                         (OmniboxFieldTrial::HQPNumMatchesScores()));
+  OmniboxFieldTrial::NumMatchesScores*
+      num_matches_to_document_specificity_score =
+          num_matches_to_document_specificity_score_override_
+              ? num_matches_to_document_specificity_score_override_
+              : &default_num_matches_to_document_specificity_score;

[Peter Kasting, 2016/12/10 02:22:26]

I feel like there might be a way to shorten all the names here and not have the
same text repeat over and over... |matches_to_specificity|?  I dunno.

[Mark P, 2016/12/11 05:11:37]

I was wondering if there was a good way to shorten the name that we'd both be
comfortable with.  It wasn't obvious.  Thank you for coming up with one.  Done.

+
+  // The floating point value below must be less than the lowest score the
+  // server would send down.
+  OmniboxFieldTrial::NumMatchesScores::const_iterator it =
+      std::upper_bound(num_matches_to_document_specificity_score->begin(),
+                       num_matches_to_document_specificity_score->end(),
+                       std::pair<size_t, double>{num_matching_pages, -1});
+  return (it != num_matches_to_document_specificity_score->end()) ? it->second
+                                                                  : 1.0;
+};
+
 // static
 float ScoredHistoryMatch::GetFinalRelevancyScore(
     float topicality_score,
     float frequency_score,
+    float specificity_score,
     const std::vector<ScoreMaxRelevance>& hqp_relevance_buckets) {
   DCHECK(hqp_relevance_buckets.size() > 0);
   DCHECK_EQ(hqp_relevance_buckets[0].first, 0.0);
 
   if (topicality_score == 0)
     return 0;
-  // Here's how to interpret intermediate_score: Suppose the omnibox
-  // has one input term.  Suppose we have a URL for which the omnibox
+  // Here's how to interpret intermediate_score: Suppose the omnibox has one
+  // input term.  Suppose the input matches many documents.  (This implies
+  // specificity_score == 1.0.)  Suppose we have a URL for which the omnibox
   // input term has a single URL hostname hit at a word boundary.  (This
   // implies topicality_score = 1.0.).  Then the intermediate_score for
   // this URL will depend entirely on the frequency_score with
@@ -651,7 +685,8 @@ float ScoredHistoryMatch::GetFinalRelevancyScore(
   //
   // The score maxes out at 1399 (i.e., cannot beat a good inlineable result
   // from HistoryURL provider).
-  const float intermediate_score = topicality_score * frequency_score;
+  const float intermediate_score =
+      topicality_score * frequency_score * specificity_score;
 
   // Find the threshold where intermediate score is greater than bucket.
   size_t i = 1;