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

chrome/renderer/translate/translate_helper.cc

Index: chrome/renderer/translate/translate_helper.cc
diff --git a/chrome/renderer/translate/translate_helper.cc b/chrome/renderer/translate/translate_helper.cc
index a01098762be583b86998c7147173d7d043122ace..b2659d53a3629840350c8901a8cc0607de28070c 100644
--- a/chrome/renderer/translate/translate_helper.cc
+++ b/chrome/renderer/translate/translate_helper.cc
@@ -127,6 +127,8 @@ void TranslateHelper::PageCaptured(const string16& contents) {
   if (language.empty())
     return;
 
+  language_determined_time_ = base::TimeTicks::Now();
+
   Send(new ChromeViewHostMsg_TranslateLanguageDetermined(
       routing_id(), language, IsPageTranslatable(&document)));
 }
@@ -439,6 +441,9 @@ void TranslateHelper::OnTranslatePage(int page_id,
                   source_lang : kAutoDetectionLanguage;
   target_lang_ = target_lang;
 
+  TranslateHelperMetrics::ReportUserActionDuration(language_determined_time_,
+                                                   base::TimeTicks::Now());
+
   if (!IsTranslateLibAvailable()) {
     // Evaluate the script to add the translation related method to the global
     // context of the page.