A working implementation of AQS (Assisted Query Stats).

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 e26e3477edd7b9b53c379d80e20cdbff116741e3..35697c0bf70f9ae6e1a5e2e4b5046413d9752888 100644
--- a/chrome/browser/autocomplete/autocomplete_match.h
+++ b/chrome/browser/autocomplete/autocomplete_match.h
@@ -15,6 +15,7 @@
 
 class AutocompleteProvider;
 class Profile;
+class SearchTermsArgs;
 class TemplateURL;
 
 // AutocompleteMatch ----------------------------------------------------------
@@ -274,6 +275,16 @@ struct AutocompleteMatch {
   // True if this match is from a previous result.
   bool from_previous;
 
+  // Optional search terms arguments used to initialize destination_url above.

[Peter Kasting, 2012/06/16 03:14:17]

Nit: How about:

"Optional search terms args.  If present,
AutocompleteController::UpdateAssistedQueryStats() will incorporate this data
with additional data it calculates and pass the completed struct to
TemplateURLRef::ReplaceSearchTerms() to reset the match's |destination_url|
after the complete set of matches in the AutocompleteResult has been chosen and
sorted.  Most providers will leave this as NULL, which will cause the
AutocompleteController to do no additional transformations."

I think this avoids the need for the second paragraph as well, but let me know
if you think it's unclear.

[Bart N, 2012/06/16 23:38:10]

Done.

+  // If present, it will be passed to TemplateURL::ReplaceSearchTerms, otherwise
+  // the destination URL won't be set.
+  //
+  // Note: The contents of this structure gets initialized at different
+  // processing stages.  For instance, the original query (input) and search
+  // terms are set by the SearchProvider, but the remaining fields,
+  // e.g. assisted_query_stats, are set later on by the AutocompleteController.
+  scoped_ptr<SearchTermsArgs> search_terms_args;
+
 #ifndef NDEBUG
   // Does a data integrity check on this match.
   void Validate() const;