[Password Generation] Sends CSS classes inside autofill proto

components/autofill/core/browser/proto/server.proto

 // Copyright 2016 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.
 
 syntax = "proto2";
 
 option optimize_for = LITE_RUNTIME;
 
 package autofill;
 
@@ skipping 16 matching lines @@
 // This message is the result of an Autofill query. It holds the field type
 // information.
 // Next available id: 7
 message AutofillQueryResponseContents {
   optional bool upload_required = 1;
   repeated group Field = 2 { required fixed32 autofill_type = 3; }
 }
 
 // This message contains information about the field types in a single form.
 // It is sent by the toolbar to contribute to the field type statistics.
-// Next available id: 19
+// Next available id: 20
 message AutofillUploadContents {
   required string client_version = 1;
   required fixed64 form_signature = 2;
 
   // True if the autofill feature was used to fill this form, false otherwise.
   required bool autofill_used = 3;
 
   // A string representing a bit array of what personal information items
   // the user has entered in the autofill settings dialog.
   // The corresponding bit is set if the user has that particular
@@ skipping 36 matching lines @@
     // The type of password generation, if it happened.
     optional PasswordGenerationType generation_type = 17;
 
     enum FormClassifierOutcome {
       NO_OUTCOME = 0;
       NON_GENERATION_ELEMENT = 1;
       GENERATION_ELEMENT = 2;
     }
     // The outcome of HTML parsing based form classifier.
     optional FormClassifierOutcome form_classifier_outcome = 18;
+
+    // The value of the class attribute on the field, if present.
+    optional string css_classes = 19;
   }
   // Signature of the form action host (e.g. Hash64Bit("example.com")).
   optional fixed64 action_signature = 13;
 
   // Signature of the form which is used for password generation debugging.
   // Currently is used when password generated on a password field of a
   // registration form is used on a password field of a login form.
   optional fixed64 login_form_signature = 14;
 
   // Whether a form submission event was observed.
   optional bool submission = 15;
 
   // The form name.
   optional string form_name = 16;
 }