UserEvent proto exploration for Translate use case.

components/sync/protocol/user_event_specifics.proto

Index: components/sync/protocol/user_event_specifics.proto
diff --git a/components/sync/protocol/user_event_specifics.proto b/components/sync/protocol/user_event_specifics.proto
index 8d3efd1b3126faa2dbe3bedd446c7c48bd381693..75091eb22b7323c2ae759cd938311b4455367be7 100644
--- a/components/sync/protocol/user_event_specifics.proto
+++ b/components/sync/protocol/user_event_specifics.proto
@@ -13,6 +13,46 @@ option optimize_for = LITE_RUNTIME;
 
 package sync_pb;
 
+// Language detection output.
+message TranslateLanguageDetection {
+  // ISO 639 language code for the guessed language based on content.
+  optional string detected_language_code = 1;
+
+  // The confidence in the language guess.
+  optional float probability = 2;
+
+  // TODO(skym): Is this important to emit? I don't understand how it is used.
+  optional int32 text_bytes = 3;
+
+  // TODO(skym): This is just calculated by the client from language and
+  // probability. Do we really need to emit?
+  optional bool is_reliable = 4;
+
+  // The |detected_language_code| can be overridden by things like html lang
+  // attribute. This field should only be set if it differs from the
+  // |detected_language_code| field.
+  optional string final_language_decision = 5;
+}
+
+// User translated a page or interacted with translate suggestion.
+message TranslateInteraction {
+  // ISO 639 language codes explicitly set by the user, and different from what
+  // was suggested.
+  optional string user_set_from_language_code = 1;
+  optional string user_set_to_language_code = 2;
+  enum Interaction {
+    UNKNOWN = 0;
+    ACCEPTED = 1;
+    ACCEPTED_ALWAYS = 2;
+    REJECTED = 3;
+    REJECTED_NEVER_LANGUAGE = 4;
+    REJECTED_NEVER_SITE = 5;
+    UNDO = 6;
+    IGNORED = 7;
+  }
+  optional Interaction interaction = 3;
+}
+
 message UserEventSpecifics {
   // Time of event, as measured on the client (unix epoch).
   optional int64 event_time_usec = 1;
@@ -24,5 +64,8 @@ message UserEventSpecifics {
   // other events belonged to.
   optional fixed64 session_id = 3;
 
-  // TODO(skym): Wrap actual event payloads in a oneof.
+  oneof event {
+    TranslateLanguageDetection translate_language_detection = 4;
+    TranslateInteraction translate_interaction = 5;
+  }
 }