[Translate] Integrate TranslateEventProto UMA logging into TranslateManager.

components/metrics/proto/translate_event.proto

Index: components/metrics/proto/translate_event.proto
diff --git a/components/metrics/proto/translate_event.proto b/components/metrics/proto/translate_event.proto
index 8dae1b0c01063fc26b7c52d330bfcd0a2b4da1d6..90bbb005b86add140a60b0f9f2749238a94182f1 100644
--- a/components/metrics/proto/translate_event.proto
+++ b/components/metrics/proto/translate_event.proto
@@ -111,6 +111,17 @@ message TranslateEventProto {
     // 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+    // The web context for the translate is no longer active.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The translate UI was not shown because the web context for the translate is no
longer active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.
@@ -131,4 +142,4 @@ message TranslateEventProto {
   // 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;
-}
+}