Revert of Revert of Componentize HistoryURLProvider/ScoredHistoryMatch.

components/omnibox/scored_history_match.h

Index: components/omnibox/scored_history_match.h
diff --git a/components/omnibox/scored_history_match.h b/components/omnibox/scored_history_match.h
new file mode 100644
index 0000000000000000000000000000000000000000..055e635d8263b0c43af6bd4a9c0fe5a1b0b2eb0f
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+++ b/components/omnibox/scored_history_match.h
@@ -0,0 +1,196 @@
+// 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.
+
+#ifndef COMPONENTS_OMNIBOX_SCORED_HISTORY_MATCH_H_
+#define COMPONENTS_OMNIBOX_SCORED_HISTORY_MATCH_H_
+
+#include <string>
+#include <vector>
+
+#include "base/strings/string16.h"
+#include "base/time/time.h"
+#include "components/history/core/browser/history_match.h"
+#include "components/history/core/browser/history_types.h"
+#include "components/omnibox/in_memory_url_index_types.h"
+#include "testing/gtest/include/gtest/gtest_prod.h"
+
+class ScoredHistoryMatchTest;
+
+// An HistoryMatch that has a score as well as metrics defining where in the
+// history item's URL and/or page title matches have occurred.
+struct ScoredHistoryMatch : public history::HistoryMatch {
+  // ScoreMaxRelevance maps from an intermediate-score to the maximum
+  // final-relevance score given to a URL for this intermediate score.
+  // This is used to store the score ranges of HQP relevance buckets.
+  // Please see GetFinalRelevancyScore() for details.
+  typedef std::pair<double, int> ScoreMaxRelevance;
+
+  // Required for STL, we don't use this directly.
+  ScoredHistoryMatch();
+
+  // Initializes the ScoredHistoryMatch with a raw score calculated for the
+  // history item given in |row| with recent visits as indicated in |visits|. It
+  // first determines if the row qualifies by seeing if all of the terms in
+  // |terms_vector| occur in |row|.  If so, calculates a raw score.  This raw
+  // score is in part determined by whether the matches occur at word
+  // boundaries, the locations of which are stored in |word_starts|.  For some
+  // terms, it's appropriate to look for the word boundary within the term. For
+  // instance, the term ".net" should look for a word boundary at the "n". 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.  |languages| is used to help
+  // parse/format the URL before looking for the terms.
+  ScoredHistoryMatch(const history::URLRow& row,
+                     const VisitInfoVector& visits,
+                     const std::string& languages,
+                     const base::string16& lower_string,
+                     const String16Vector& terms_vector,
+                     const WordStarts& terms_to_word_starts_offsets,
+                     const RowWordStarts& word_starts,
+                     bool is_url_bookmarked,
+                     base::Time now);
+
+  ~ScoredHistoryMatch();
+
+  // Compares two matches by score.  Functor supporting URLIndexPrivateData's
+  // HistoryItemsForTerms function.  Looks at particular fields within
+  // with url_info to make tie-breaking a bit smarter.
+  static bool MatchScoreGreater(const ScoredHistoryMatch& m1,
+                                const ScoredHistoryMatch& m2);
+
+  // Returns |term_matches| after removing all matches that are not at a
+  // word break that are in the range [|start_pos|, |end_pos|).
+  // start_pos == string::npos is treated as start_pos = length of string.
+  // (In other words, no matches will be filtered.)
+  // end_pos == string::npos is treated as end_pos = length of string.
+  static TermMatches FilterTermMatchesByWordStarts(
+      const TermMatches& term_matches,
+      const WordStarts& terms_to_word_starts_offsets,
+      const WordStarts& word_starts,
+      size_t start_pos,
+      size_t end_pos);
+
+  // The maximum number of recent visits to examine in GetFrequency().
+  // Public so url_index_private_data.cc knows how many visits it is
+  // expected to deliver (at minimum) to this class.
+  static const size_t kMaxVisitsToScore;
+
+  // An interim score taking into consideration location and completeness
+  // of the match.
+  int raw_score;
+
+  // Both these TermMatches contain the set of matches that are considered
+  // important.  At this time, that means they exclude mid-word matches
+  // except in the hostname of the URL.  (Technically, during early
+  // construction of ScoredHistoryMatch, they may contain all matches, but
+  // unimportant matches are eliminated by GetTopicalityScore(), called
+  // during construction.)
+
+  // Term matches within the URL.
+  TermMatches url_matches;
+  // Term matches within the page title.
+  TermMatches title_matches;
+
+  // True if this is a candidate for in-line autocompletion.
+  bool can_inline;
+
+ private:
+  friend class ScoredHistoryMatchTest;
+  FRIEND_TEST_ALL_PREFIXES(ScoredHistoryMatchTest, GetFinalRelevancyScore);
+  FRIEND_TEST_ALL_PREFIXES(ScoredHistoryMatchTest, GetHQPBucketsFromString);
+  FRIEND_TEST_ALL_PREFIXES(ScoredHistoryMatchTest, ScoringBookmarks);
+  FRIEND_TEST_ALL_PREFIXES(ScoredHistoryMatchTest, ScoringScheme);
+  FRIEND_TEST_ALL_PREFIXES(ScoredHistoryMatchTest, ScoringTLD);
+
+  // Initialize ScoredHistoryMatch statics. Must be called before any other
+  // method of ScoredHistoryMatch and before creating any instances.
+  static void Init();
+
+  // Return a topicality score based on how many matches appear in the url and
+  // the page's title and where they are (e.g., at word boundaries).  Revises
+  // url_matches and title_matches in the process so they only reflect matches
+  // used for scoring.  (For instance, some mid-word matches are not given
+  // credit in scoring.)
+  float GetTopicalityScore(const int num_terms,
+                           const base::string16& cleaned_up_url,
+                           const WordStarts& terms_to_word_starts_offsets,
+                           const RowWordStarts& word_starts);
+
+  // Returns a recency score based on |last_visit_days_ago|, which is
+  // how many days ago the page was last visited.
+  float GetRecencyScore(int last_visit_days_ago) const;
+
+  // Examines the first kMaxVisitsToScore and return a score (higher is
+  // better) based the rate of visits, whether the page is bookmarked, and
+  // how often those visits are typed navigations (i.e., explicitly
+  // invoked by the user).  |now| is passed in to avoid unnecessarily
+  // recomputing it frequently.
+  float GetFrequency(const base::Time& now,
+                     const bool bookmarked,
+                     const VisitInfoVector& visits) const;
+
+  // Combines the two 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,
+      const std::vector<ScoreMaxRelevance>& hqp_relevance_buckets);
+
+  // Initializes the HQP experimental params: |hqp_relevance_buckets_|
+  // to default buckets. If hqp experimental scoring is enabled, it
+  // fetches the |hqp_experimental_scoring_enabled_|, |topicality_threshold_|
+  // and |hqp_relevance_buckets_| from omnibox field trials.
+  static void InitHQPExperimentalParams();
+
+  // Helper function to parse the string containing the scoring buckets.
+  // For example,
+  // String: "0.0:400,1.5:600,12.0:1300,20.0:1399"
+  // Buckets: vector[(0.0, 400),(1.5,600),(12.0,1300),(20.0,1399)]
+  // Returns false, in case if it fail to parse the string.
+  static bool GetHQPBucketsFromString(
+      const std::string& buckets_str,
+      std::vector<ScoreMaxRelevance>* hqp_buckets);
+
+  // If true, assign raw scores to be max(whatever it normally would be, a
+  // score that's similar to the score HistoryURL provider would assign).
+  static bool also_do_hup_like_scoring_;
+
+  // Untyped visits to bookmarked pages score this, compared to 1 for
+  // untyped visits to non-bookmarked pages and 20 for typed visits.
+  static int bookmark_value_;
+
+  // True if we should fix certain bugs in frequency scoring.
+  static bool fix_frequency_bugs_;
+
+  // If true, we allow input terms to match in the TLD (e.g., ".com").
+  static bool allow_tld_matches_;
+
+  // If true, we allow input terms to match in the scheme (e.g., "http://").
+  static bool allow_scheme_matches_;
+
+  // The number of title words examined when computing topicality scores.
+  // Words beyond this number are ignored.
+  static size_t num_title_words_to_allow_;
+
+  // True, if hqp experimental scoring is enabled.
+  static bool hqp_experimental_scoring_enabled_;
+
+  // |topicality_threshold_| is used to control the topicality scoring.
+  // If |topicality_threshold_| > 0, then URLs with topicality-score < threshold
+  // are given topicality score of 0. By default it is initalized to -1.
+  static float topicality_threshold_;
+
+  // |hqp_relevance_buckets_| gives mapping from (topicality*frequency)
+  // to the final relevance scoring. Please see GetFinalRelevancyScore()
+  // for more details and scoring method.
+  static std::vector<ScoreMaxRelevance>* hqp_relevance_buckets_;
+};
+typedef std::vector<ScoredHistoryMatch> ScoredHistoryMatches;
+
+#endif  // COMPONENTS_OMNIBOX_SCORED_HISTORY_MATCH_H_