Omnibox: In UMA logs, record typed_count of URLS.

chrome/browser/autocomplete/autocomplete_match.h

Index: chrome/browser/autocomplete/autocomplete_match.h
diff --git a/chrome/browser/autocomplete/autocomplete_match.h b/chrome/browser/autocomplete/autocomplete_match.h
index cef1892e7876f7f5acaffae59c238b4d8e448cf3..e26e3477edd7b9b53c379d80e20cdbff116741e3 100644
--- a/chrome/browser/autocomplete/autocomplete_match.h
+++ b/chrome/browser/autocomplete/autocomplete_match.h
@@ -203,6 +203,12 @@ struct AutocompleteMatch {
   // rather than being a fairly fixed value defined by the table above.
   int relevance;
 
+  // How many times this result was typed in / selected from the omnibox.
+  // Only set for some providers and result_types.  If it is not set,
+  // its value is -1.  At the time of writing this comment, it is only
+  // set for matches from HistoryURL and HistoryQuickProvider.
+  int typed_count;
+
   // True if the user should be able to delete this match.
   bool deletable;