[Translate] Integrate TranslateEventProto UMA logging into TranslateManager.

components/translate/core/browser/translate_manager.h

Index: components/translate/core/browser/translate_manager.h
diff --git a/components/translate/core/browser/translate_manager.h b/components/translate/core/browser/translate_manager.h
index 502474f101c0eb24279b7e0edab45881f8e22f44..69618947943a46b06a2226ea047d030944a3b817 100644
--- a/components/translate/core/browser/translate_manager.h
+++ b/components/translate/core/browser/translate_manager.h
@@ -15,6 +15,7 @@
 #include "base/gtest_prod_util.h"
 #include "base/macros.h"
 #include "base/memory/weak_ptr.h"
+#include "components/metrics/proto/translate_event.pb.h"
 #include "components/translate/core/browser/language_state.h"
 #include "components/translate/core/common/translate_errors.h"
 
@@ -58,6 +59,10 @@ class TranslateManager {
   // messages to the renderer.
   void set_current_seq_no(int page_seq_no) { page_seq_no_ = page_seq_no; }
 
+  metrics::TranslateEventProto* mutable_translate_event() {
+    return &translate_event_;
+  }
+
   // Returns the language to translate to. The language returned is the
   // first language found in the following list that is supported by the
   // translation service:
@@ -108,6 +113,10 @@ class TranslateManager {
   // Gets the LanguageState associated with the TranslateManager
   LanguageState& GetLanguageState();
 
+  // Record an event of the given |event_type| using the currently saved
+  // |translate_event_| as context.
+  void RecordTranslateEvent(metrics::TranslateEventProto::EventType event_type);
+
   // By default, don't offer to translate in builds lacking an API key. For
   // testing, set to true to offer anyway.
   static void SetIgnoreMissingKeyForTesting(bool ignore);
@@ -138,6 +147,11 @@ class TranslateManager {
                                       bool success,
                                       const std::string& data);
 
+  // Helper function to initialize a translate event metric proto.
+  void InitTranslateEvent(const std::string& src_lang,
+                          const std::string& dst_lang,
+                          const TranslatePrefs& translate_prefs);
+
   // Sequence number of the current page.
   int page_seq_no_;
 
@@ -149,6 +163,8 @@ class TranslateManager {
 
   LanguageState language_state_;
 
+  metrics::TranslateEventProto translate_event_;
+
   base::WeakPtrFactory<TranslateManager> weak_method_factory_;
 
   // By default, don't offer to translate in builds lacking an API key. For