[Autofill/Autocomplete Feature] Substring matching instead of prefix matching.

components/autofill/core/browser/suggestion.h

Index: components/autofill/core/browser/suggestion.h
diff --git a/components/autofill/core/browser/suggestion.h b/components/autofill/core/browser/suggestion.h
index b9626449115e9fbf7dd2a2000c60b029ff2ae413..c9c43a24630494c6839fba5b05ed7496bb7e1741 100644
--- a/components/autofill/core/browser/suggestion.h
+++ b/components/autofill/core/browser/suggestion.h
@@ -31,6 +31,11 @@ struct SuggestionBackendID {
 
 struct Suggestion {
  public:
+  enum MatchMode {
+    PREFIX_MATCH,    // for prefix matched suggestions;
+    SUBSTRING_MATCH  // for substring matched suggestions;
+  };
+
   Suggestion();
 
   // Copy constructor for STL containers.
@@ -60,6 +65,7 @@ struct Suggestion {
   base::string16 value;
   base::string16 label;
   base::string16 icon;
+  MatchMode match;
 };
 
 }  // namespace autofill