[Translate] Integrate TranslateEventProto UMA logging into TranslateManager.

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";
@@ skipping 93 matching lines @@
     // many times.
     LANGUAGE_DISABLED_BY_AUTO_BLACKLIST = 14;
     // The translation was not offered because Ranker dismissed it.
     DISABLED_BY_RANKER = 15;
     // The translation was not offered because the source or target
     // language is not supported.
     UNSUPPORTED_LANGUAGE = 16;
     // The translation was not offered because the URL is not
     // supported (e.g. New Tab Page).
     UNSUPPORTED_URL = 17;
+    // The previous page was in the same language, so the translate UI was
+    // suppressed.
+    MATCHES_PREVIOUS_LANGUAGE = 18;
+    // The web context for the translate is no longer active.

[hamelphi, 2016/10/17 16:14:40]

Please describe explicitly what happened with Translate UI (i.e. shown or not
shown) in the descriptions. This will help understand the event type without
understanding the details of these specific situations.

E.g.
The translate UI was not shown because the web context for the translate is no
longer active

[Roger McFarlane (Chromium), 2016/10/24 19:01:52]

Done.

+    WEBCONTENTS_NOT_ACTIVE = 19;
+    // The browser context for translate prompt is no longer active.
+    BROSWER_WINDOW_NOT_ACTIVE = 20;
+    // The browser window is minimized.
+    BROWSER_WINDOW_MINIMIZED = 21;
+    // The focus in on an editable field.

[rkaplow, 2016/10/17 14:48:20]

not sure what this last enum is really trying to say

[Roger McFarlane (Chromium), 2016/10/24 19:01:52]

Done.

+    EDITABLE_FIELD_IN_FOCUS = 22;
   }
 
   // Event received from translate UI.
   optional EventType event_type = 10;
 
   // 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;
-}
+}