[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 6077185018ea1be0c3b1d62bc758ba990de13790..ebf16073b8abf965eb581cfdb58692cc7ec7f965 100644
--- a/components/autofill/core/browser/suggestion.h
+++ b/components/autofill/core/browser/suggestion.h
@@ -17,6 +17,11 @@ class CreditCard;
 
 struct Suggestion {
  public:
+  enum MatchMode {
+    PREFIX_MATCH,    // for prefix matched suggestions;
+    SUBSTRING_MATCH  // for substring matched suggestions;
+  };
+
   Suggestion();
 
   // Copy constructor for STL containers.
@@ -46,6 +51,7 @@ struct Suggestion {
   base::string16 value;
   base::string16 label;
   base::string16 icon;
+  MatchMode match;
 };
 
 }  // namespace autofill