Omnibox - Boost Frequency Scores Based on Number of Matching Pages

components/omnibox/browser/scored_history_match.h

Index: components/omnibox/browser/scored_history_match.h
diff --git a/components/omnibox/browser/scored_history_match.h b/components/omnibox/browser/scored_history_match.h
index dacd31cec537b30c501c35a6410bca55cbe20d96..dec472f0a77a4e19b99efadbcb949639d23b66b3 100644
--- a/components/omnibox/browser/scored_history_match.h
+++ b/components/omnibox/browser/scored_history_match.h
@@ -16,6 +16,7 @@
 #include "components/history/core/browser/history_match.h"
 #include "components/history/core/browser/history_types.h"
 #include "components/omnibox/browser/in_memory_url_index_types.h"
+#include "components/omnibox/browser/omnibox_field_trial.h"
 
 class ScoredHistoryMatchTest;
 
@@ -43,9 +44,11 @@ struct ScoredHistoryMatch : public history::HistoryMatch {
   // These offsets (".net" should have an offset of 1) come from
   // |terms_to_word_starts_offsets|. |is_url_bookmarked| indicates whether the
   // match's URL is referenced by any bookmarks, which can also affect the raw
-  // score.  The raw score allows the matches to be ordered and can be used to
-  // influence the final score calculated by the client of this index.  If the
-  // row does not qualify the raw score will be 0.
+  // score.  |num_matching_pages| indicates how many URLs in the eligible URL
+  // database match the user's input; it can also affect the raw score.  The raw
+  // score allows the matches to be ordered and can be used to influence the
+  // final score calculated by the client of this index.  If the row does not
+  // qualify the raw score will be 0.
   ScoredHistoryMatch(const history::URLRow& row,
                      const VisitInfoVector& visits,
                      const base::string16& lower_string,
@@ -53,6 +56,7 @@ struct ScoredHistoryMatch : public history::HistoryMatch {
                      const WordStarts& terms_to_word_starts_offsets,
                      const RowWordStarts& word_starts,
                      bool is_url_bookmarked,
+                     size_t num_matching_pages,
                      base::Time now);
 
   ~ScoredHistoryMatch();
@@ -93,6 +97,7 @@ struct ScoredHistoryMatch : public history::HistoryMatch {
 
  private:
   friend class ScoredHistoryMatchTest;
+  FRIEND_TEST_ALL_PREFIXES(ScoredHistoryMatchTest, GetDocumentSpecificityScore);
   FRIEND_TEST_ALL_PREFIXES(ScoredHistoryMatchTest, GetFinalRelevancyScore);
   FRIEND_TEST_ALL_PREFIXES(ScoredHistoryMatchTest, GetFrequency);
   FRIEND_TEST_ALL_PREFIXES(ScoredHistoryMatchTest, GetHQPBucketsFromString);
@@ -128,13 +133,18 @@ struct ScoredHistoryMatch : public history::HistoryMatch {
                      const bool bookmarked,
                      const VisitInfoVector& visits) const;
 
-  // Combines the two component scores into a final score that's
+  // Returns a document specificity score based on how many pages matched the
+  // user's input.
+  float GetDocumentSpecificityScore(const size_t num_matching_pages) const;

[Peter Kasting, 2016/12/06 05:19:30]

I'd avoid declaring the parameter here const.

[Mark P, 2016/12/08 00:21:31]

Done.

+
+  // Combines the three component scores into a final score that's
   // an appropriate value to use as a relevancy score. Scoring buckets are
   // specified through |hqp_relevance_buckets|. Please see the function
   // implementation for more details.
   static float GetFinalRelevancyScore(
       float topicality_score,
       float frequency_score,
+      float specificity_score,
       const std::vector<ScoreMaxRelevance>& hqp_relevance_buckets);
 
   // Initializes the HQP experimental params: |hqp_relevance_buckets_|
@@ -171,6 +181,11 @@ struct ScoredHistoryMatch : public history::HistoryMatch {
   // sum of visit scores instead of the weighted average.
   static bool frequency_uses_sum_;
 
+  // A mapping from the number of matching pages to their associated document
+  // specificity scores.  See omnibox_field_trial.h for more details.
+  static OmniboxFieldTrial::NumMatchesScores*
+      num_matches_to_document_specificity_score_;
+
   // The maximum number of recent visits to examine in GetFrequency().
   static size_t max_visits_to_score_;