autocomplete: Make ContactProvider rank contacts by affinity

chrome/browser/autocomplete/contact_provider_chromeos.h

Index: chrome/browser/autocomplete/contact_provider_chromeos.h
diff --git a/chrome/browser/autocomplete/contact_provider_chromeos.h b/chrome/browser/autocomplete/contact_provider_chromeos.h
index 9880aa0bb42274c30e73b36096858b64419ec9b4..1a14a386c34cc0bf8c84b68d7d2f404765d63368 100644
--- a/chrome/browser/autocomplete/contact_provider_chromeos.h
+++ b/chrome/browser/autocomplete/contact_provider_chromeos.h
@@ -48,6 +48,9 @@ class ContactProvider : public AutocompleteProvider,
 
   virtual ~ContactProvider();
 
+  // Returns true if |a|'s affinity is greater than |b|'s affinity.
+  static bool CompareAffinity(const ContactData& a, const ContactData& b);
+
   // Updates |contacts_| to match the contacts currently reported by
   // ContactManager.
   void RefreshContacts();
@@ -65,7 +68,7 @@ class ContactProvider : public AutocompleteProvider,
 
   base::WeakPtr<contacts::ContactManagerInterface> contact_manager_;
 
-  // Contacts through which we search.
+  // Contacts through which we search, ordered by descending affinity.
   ContactDataVector contacts_;
 
   DISALLOW_COPY_AND_ASSIGN(ContactProvider);