Track confidence calculations better. Reduce minimum user text length.

chrome/browser/autocomplete/network_action_predictor.h

Index: chrome/browser/autocomplete/network_action_predictor.h
diff --git a/chrome/browser/autocomplete/network_action_predictor.h b/chrome/browser/autocomplete/network_action_predictor.h
index 20b570815752a92fe6ceffdeb6d59db08cb3a124..ceb9dadba88a18a158b7daf64d84b4cdc30b9b86 100644
--- a/chrome/browser/autocomplete/network_action_predictor.h
+++ b/chrome/browser/autocomplete/network_action_predictor.h
@@ -141,9 +141,12 @@ class NetworkActionPredictor
   bool TryDeleteOldEntries(HistoryService* service);
 
   // Uses local caches to calculate an exact percentage prediction that the user
-  // will take a particular match given what they have typed.
-  double ExactAlgorithm(const string16& user_text,
-                        const AutocompleteMatch& match) const;
+  // will take a particular match given what they have typed. |is_in_db| is set
+  // to differentiate trivial zero results resulting from a match not being
+  // found from actual zero results where the calculation returns 0.0.
+  double CalculateConfidence(const string16& user_text,
+                             const AutocompleteMatch& match,
+                             bool* is_in_db) const;
 
   // Adds a row to the database and caches.
   void AddRow(const DBCacheKey& key,