Translate: add UMA to measure duration time of infobar user action

chrome/renderer/translate/translate_helper.h

Index: chrome/renderer/translate/translate_helper.h
diff --git a/chrome/renderer/translate/translate_helper.h b/chrome/renderer/translate/translate_helper.h
index f0ae0d91bdb0062c5fe80710051963ba2707b9cc..0c0245cc7388cde5a17dd46ea35d2c0b67f78461 100644
--- a/chrome/renderer/translate/translate_helper.h
+++ b/chrome/renderer/translate/translate_helper.h
@@ -151,6 +151,10 @@ class TranslateHelper : public content::RenderViewObserver {
   std::string source_lang_;
   std::string target_lang_;
 
+  // Time when a page langauge is determined. This is used to know a duration
+  // time from showing infobar to requesting translation.
+  base::TimeTicks language_determined_time_;
+
   // Method factory used to make calls to TranslatePageImpl.
   base::WeakPtrFactory<TranslateHelper> weak_method_factory_;