Log Autofill.Quality.*.ByFieldType by predicted type for unknown data.

components/autofill/core/browser/field_types.h

Index: components/autofill/core/browser/field_types.h
diff --git a/components/autofill/core/browser/field_types.h b/components/autofill/core/browser/field_types.h
index cee305fcda51c25dfe6c443692ebd96ecd1e20a3..33d1cf7703edf3f161d0c71674b977755706702d 100644
--- a/components/autofill/core/browser/field_types.h
+++ b/components/autofill/core/browser/field_types.h
@@ -163,9 +163,13 @@ enum ServerFieldType {
   // forms.
   CONFIRMATION_PASSWORD = 95,
 
+  // The data entered by the user matches multiple pieces of autofill data,
+  // none of which were predicted by autofill.
+  AMBIGUOUS_TYPE = 96,

[Mathieu, 2017/05/31 20:07:18]

you'll need to modify the server version according to the top level comment here

[Roger McFarlane (Chromium), 2017/06/01 20:23:16]

Acknowledged.

+
   // No new types can be added without a corresponding change to the Autofill
   // server.
-  MAX_VALID_FIELD_TYPE = 96,
+  MAX_VALID_FIELD_TYPE = 97,
 };
 
 // The list of all HTML autocomplete field type hints supported by Chrome.