Do not autofill element when there is no autofill suggestion from profile

components/autofill/core/browser/autofill_manager.cc

 // Copyright 2013 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "components/autofill/core/browser/autofill_manager.h"
 
 #include <stddef.h>
 
 #include <limits>
 #include <map>
@@ skipping 539 matching lines @@
           !is_credit_card &&
           !value.empty() &&
           (result.fields[i] == field ||
            result.fields[i].form_control_type == "select-one" ||
            result.fields[i].value.empty());
       if (AutofillField::FillFormField(
           *cached_field, value, app_locale_, &result.fields[i])) {
         // Mark the cached field as autofilled, so that we can detect when a
         // user edits an autofilled field (for metrics).
         form_structure->field(i)->is_autofilled = true;
+        // Mark the "select-one" field as autofilled when a non-empty value is
+        // assigned to it.

[Ilya Sherman, 2014/06/02 23:51:00]

Is there any harm to doing this for all the autofilled fields, rather than only
for <select> fields?

+        if (result.fields[i].form_control_type == "select-one")
+          result.fields[i].is_autofilled = true;
 
         if (should_notify)
           manager_delegate_->DidFillOrPreviewField(value, profile_full_name);
       }
     }
   }
 
   autofilled_form_signatures_.push_front(form_structure->FormSignature());
   // Only remember the last few forms that we've seen, both to avoid false
   // positives and to avoid wasting memory.
@@ skipping 568 matching lines @@
     return false;
 
   // Disregard forms that we wouldn't ever autofill in the first place.
   if (!form.ShouldBeParsed(true))
     return false;
 
   return true;
 }
 
 }  // namespace autofill