Translate: UMA for "Show original"

chrome/browser/translate/translate_infobar_delegate.cc

Index: chrome/browser/translate/translate_infobar_delegate.cc
diff --git a/chrome/browser/translate/translate_infobar_delegate.cc b/chrome/browser/translate/translate_infobar_delegate.cc
index bfeba33ce41288fb1b9477662dbe66e829122b1a..3a2b8ca1dc7a067bc97f8d92a07a89276b9e7e14 100644
--- a/chrome/browser/translate/translate_infobar_delegate.cc
+++ b/chrome/browser/translate/translate_infobar_delegate.cc
@@ -25,7 +25,11 @@ using content::NavigationEntry;
 
 namespace {
 
-const char kTranslateShowErrorInfobar[] = "Translate.ShowErrorInfobar";
+const char kDeclineTranslate[] = "Translate.DeclineTranslate";
+const char kCloseInfobar[] = "Translate.DeclineTranslateCloseInfobar";
+const char kRevertTranslation[] = "Translate.RevertTranslation";
+const char kShowErrorInfobar[] = "Translate.ShowErrorInfobar";
+const char kPerformTranslate[] = "Translate.Translate";
 
 }  // namespace
 
@@ -87,12 +91,14 @@ void TranslateInfoBarDelegate::Translate() {
                                                  original_language_code(),
                                                  target_language_code());
 
-  UMA_HISTOGRAM_COUNTS("Translate.Translate", 1);
+  UMA_HISTOGRAM_COUNTS(kPerformTranslate, 1);
 }
 
 void TranslateInfoBarDelegate::RevertTranslation() {
   TranslateManager::GetInstance()->RevertTranslation(web_contents());
   RemoveSelf();
+
+  UMA_HISTOGRAM_COUNTS(kRevertTranslation, 1);

[jar (doing other things), 2013/05/23 17:20:00]

This pattern of trying to use histograms as single bucket counters is actually
problematic in several ways.

First of all, you really want to see the counts next to each other, so using an
enumerated histogram gets you these counters visualized exactly as you actually
need them: Several counters next to one another, providing normalization factors
for each other.

Second, it is wasteful of both run-time memory, and backend dashboard-pipeline
memory.  The cost of "an additional enumerated bucket" is about 12 bytes in the
browser.  Adding another histogram is surely in the range of a few hundred bytes
minimum to the browser, and a similar jump in cost/complexity in the processing
pipeline :-(.

Lastly, you've accidentally used UMA_HISTOGRAM_COUNTS(), which creates space for
50 buckets.  That costs about 500-600 bytes.  Much better in this poor usage
pattern would be UMA_HISOGRAM_BOOLEAN(), which at least only creates one bucket.

Bottom line: You really should use an enumerated histogram.  If you really want
to use up a few KB of RAM space extra, and stay with this pattern, you should at
least use UMA_HISTOGRAM_BOOLEAN("foo", true);

 }
 
 void TranslateInfoBarDelegate::ReportLanguageDetectionError() {
@@ -115,7 +121,7 @@ void TranslateInfoBarDelegate::TranslationDeclined() {
       TranslateTabHelper::FromWebContents(web_contents());
   translate_tab_helper->language_state().set_translation_declined(true);
 
-  UMA_HISTOGRAM_COUNTS("Translate.DeclineTranslate", 1);
+  UMA_HISTOGRAM_COUNTS(kDeclineTranslate, 1);
 }
 
 bool TranslateInfoBarDelegate::InTranslateNavigation() {
@@ -194,7 +200,7 @@ string16 TranslateInfoBarDelegate::GetMessageInfoBarText() {
   }
 
   DCHECK_EQ(TRANSLATION_ERROR, infobar_type_);
-  UMA_HISTOGRAM_ENUMERATION(kTranslateShowErrorInfobar,
+  UMA_HISTOGRAM_ENUMERATION(kShowErrorInfobar,
                             error_type_,
                             TranslateErrors::TRANSLATE_ERROR_MAX);
   switch (error_type_) {
@@ -374,7 +380,7 @@ void TranslateInfoBarDelegate::InfoBarDismissed() {
 
   // The user closed the infobar without clicking the translate button.
   TranslationDeclined();
-  UMA_HISTOGRAM_COUNTS("Translate.DeclineTranslateCloseInfobar", 1);
+  UMA_HISTOGRAM_COUNTS(kCloseInfobar, 1);
 }
 
 int TranslateInfoBarDelegate::GetIconID() const {