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 161e1f6ac901ce337dd875a90414c8f073ffc706..3ebd7cbcfcc8c392b5efaf7ebad6bdee892285d0 100644
--- a/chrome/renderer/translate/translate_helper.cc
+++ b/chrome/renderer/translate/translate_helper.cc
@@ -126,6 +126,8 @@ 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)));
 }
@@ -438,6 +440,9 @@ 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.