Add confidence to AutocompleteMatch.

chrome/browser/autocomplete/history_contents_provider.h

Index: chrome/browser/autocomplete/history_contents_provider.h
diff --git a/chrome/browser/autocomplete/history_contents_provider.h b/chrome/browser/autocomplete/history_contents_provider.h
index 7ceb0b90639758ce5eff2c5d683d37af39068001..f4fd334afd17bcadce9fea75f681a328fe9f9d10 100644
--- a/chrome/browser/autocomplete/history_contents_provider.h
+++ b/chrome/browser/autocomplete/history_contents_provider.h
@@ -35,6 +35,22 @@ class HistoryContentsProvider : public HistoryProvider {
   virtual void Stop() OVERRIDE;
 
  private:
+  // When processing the results from the history query, this structure points
+  // to a single result. It allows the results to be sorted and processed
+  // without modifying the larger and slower results structure.
+  struct MatchReference {
+    MatchReference(const history::URLResult* result,
+                   int relevance,
+                   float confidence);
+
+    static bool CompareRelevance(const MatchReference& lhs,
+                                 const MatchReference& rhs);
+
+    const history::URLResult* result;
+    int relevance;  // Score of relevance computed by CalculateRelevance.
+    float confidence;  // Confidence computed by CalculateConfidence.
+  };
+
   virtual ~HistoryContentsProvider();
 
   void QueryComplete(HistoryService::Handle handle,
@@ -45,8 +61,7 @@ class HistoryContentsProvider : public HistoryProvider {
   void ConvertResults();
 
   // Creates and returns an AutocompleteMatch from a MatchingPageResult.
-  AutocompleteMatch ResultToMatch(const history::URLResult& result,
-                                  int score);
+  AutocompleteMatch ResultToMatch(const MatchReference& match_reference);
 
   // Adds ACMatchClassifications to match from the offset positions in
   // page_result.
@@ -57,6 +72,12 @@ class HistoryContentsProvider : public HistoryProvider {
   // chart in autocomplete.h for the list of values this returns.
   int CalculateRelevance(const history::URLResult& result);
 
+  // Calculates and returns the confidence for a particular result. This is
+  // calculated by comparing the result's |visit_count| to that of all the
+  // results.
+  float CalculateConfidence(const history::URLResult& result,
+                            const history::QueryResults& results) const;

[mrossetti, 2011/08/09 23:40:43]

Same suggestion as for the HistoryQuickProvider: calculate the sum of the scores
in the ConvertResults function instead of recalculating it here for each match.
Or do you imagine that the confidence calculation might transmogrify into
something more complex?

[dominich, 2011/08/10 16:10:13]

There's a very good chance the details of the calculation will change. This
first version is deliberately naive to see if it alone can improve the success
rate of prerendering from the omnibox.

+
   // Queries the bookmarks for any bookmarks whose title matches input. All
   // matches are added directly to results_.
   void QueryBookmarks(const AutocompleteInput& input);