Allow TranslateRanker to override decisions taken by heuristics.

components/metrics/proto/translate_event.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.
 //
 // Stores information about translate UI, translate Ranekr and user interaction.
 
 syntax = "proto2";
 
 option optimize_for = LITE_RUNTIME;
 option java_outer_classname = "TranslateEventProtos";
 option java_package = "org.chromium.components.metrics";
 
 package metrics;
 
 // Stores information about a single interaction between a user and
 // the Translate UI. Contains features used by Translate Ranker for
 // inference, information about the ranker model and its decision, as
 // well as user or automated feedback from the Translate UI.
-// Next tag: 15
+// Next tag: 16
 message TranslateEventProto {
   // Language strings are two or three letter codes, with sometimes an extra
   // suffix (for e.g. chinese zh-TW or zh-CN). See
   // https://cs.chromium.org/chromium/src/components/translate/core/browser/translate_language_list.cc
   // for a list of supported languages.
   // Source language of the translation.
   optional string source_language = 1;
   // Target language of the translation.
   optional string target_language = 2;
 
@@ skipping 99 matching lines @@
     // The translate UI was not shown because the web context for the translate
     // prompt is no longer active.
     WEB_CONTENTS_NOT_ACTIVE = 22;
     // The translate UI was not shown because the user is editing a form field.
     EDITABLE_FIELD_IS_ACTIVE = 23;
   }
 
   // Event received from translate UI.
   optional EventType event_type = 10;
 
+  // Decisions that have been overriden by translate ranker (e.g.
+  // LANGUAGE_DISABLED_BY_AUTO_BLACKLIST).
+  repeated EventType decision_overrides = 15;
+
   // The timestamp for the event, in seconds.
   // This value comes from Chromium's TimeTicks::Now(), which is an abstract
   // time value that is guaranteed to always be increasing (regardless of
   // Daylight Saving Time or any other changes to the system clock).
   // These numbers are only comparable within a session.  To sequence events
   // across sessions, order by the |session_id| from the
   // ChromeUserMetricsExtension message.
   optional int64 event_timestamp_sec = 11;
 
   // Modified source language, if the user changed it. If changed more than
   // once, we only keep the last one.
   optional string modified_source_language = 12;
   // Modified target language, if the user changed it. If changed more than
   // once, we only keep the last one.
   optional string modified_target_language = 13;
 }