Remove Translate.UndisplayableLanguage histogram.

This CL removes the unused histogram Translate.UndisplayableLanguage.

This histogram records languages that can be translated but are not
displayable in the current UI language. This happens because some
Chrome languages do not have language name translations in their ICU
file (or in java.util for Android).

We don't need a histogram to capture these.  We can find them with a
script.  Also, this histogram doesn't report which UI language the
language name isn't available in which is what we would need to make
fix the problem.

Bug: 1037346
Change-Id: I995611743c5f37d7a6fc0cca67a55f6356738933
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2617217
Commit-Queue: Trevor  Perrier <perrier@chromium.org>
Reviewed-by: Megan Jablonski <megjablon@chromium.org>
Reviewed-by: Tarun Bansal <tbansal@chromium.org>
Cr-Commit-Position: refs/heads/master@{#842759}

components/translate/core/browser/translate_browser_metrics.cc

@@ -22,8 +22,6 @@ const char kTranslateLanguageDetectionContentLength[] =
     "Translate.LanguageDetection.ContentLength";
 const char kTranslateLocalesOnDisabledByPrefs[] =
     "Translate.LocalesOnDisabledByPrefs";
-const char kTranslateUndisplayableLanguage[] =
-    "Translate.UndisplayableLanguage";
 const char kTranslateUnsupportedLanguageAtInitiation[] =
     "Translate.UnsupportedLanguageAtInitiation";
 const char kTranslateSourceLanguage[] = "Translate.SourceLanguage";
@@ -65,11 +63,6 @@ void ReportLocalesOnDisabledByPrefs(base::StringPiece locale) {
       language::LanguageUsageMetrics::ToLanguageCode(locale));
 }
 
-void ReportUndisplayableLanguage(base::StringPiece language) {
-  int language_code = language::LanguageUsageMetrics::ToLanguageCode(language);
-  base::UmaHistogramSparse(kTranslateUndisplayableLanguage, language_code);
-}
-
 void ReportUnsupportedLanguageAtInitiation(base::StringPiece language) {
   int language_code = language::LanguageUsageMetrics::ToLanguageCode(language);
   base::UmaHistogramSparse(kTranslateUnsupportedLanguageAtInitiation,

components/translate/core/browser/translate_browser_metrics.h

@@ -116,10 +116,6 @@ void ReportLanguageDetectionContentLength(size_t length);
 
 void ReportLocalesOnDisabledByPrefs(base::StringPiece locale);
 
-// Called when Chrome Translate server sends the language list which includes
-// a undisplayable language in the user's locale.
-void ReportUndisplayableLanguage(base::StringPiece language);
-
 void ReportUnsupportedLanguageAtInitiation(base::StringPiece language);
 
 // Called when a request is sent to the translate server to report the source

components/translate/core/browser/translate_browser_metrics_unittest.cc

@@ -372,15 +372,6 @@ TEST(TranslateBrowserMetricsTest, ReportedLocalesOnDisabledByPrefs) {
   EXPECT_EQ(1, recorder.GetCount(ENGLISH));
 }
 
-TEST(TranslateBrowserMetricsTest, ReportedUndisplayableLanguage) {
-  const int ENGLISH = 25966;
-
-  MetricsRecorder recorder("Translate.UndisplayableLanguage");
-  EXPECT_EQ(0, recorder.GetTotalCount());
-  translate::TranslateBrowserMetrics::ReportUndisplayableLanguage("en");
-  EXPECT_EQ(1, recorder.GetCount(ENGLISH));
-}
-
 TEST(TranslateBrowserMetricsTest, ReportedUnsupportedLanguageAtInitiation) {
   const int ENGLISH = 25966;
 

components/translate/core/browser/translate_language_list.cc

@@ -341,7 +341,7 @@ bool TranslateLanguageList::SetSupportedLanguages(
   for (const auto& kv_pair : target_languages->DictItems()) {
     const std::string& lang = kv_pair.first;
     if (!l10n_util::IsLocaleNameTranslated(lang.c_str(), locale)) {
-      TranslateBrowserMetrics::ReportUndisplayableLanguage(lang);
+      // Don't include languages not displayable in current UI language.
       continue;
     }
     supported_languages_.push_back(lang);

tools/metrics/histograms/histograms_xml/translate/histograms.xml

@@ -925,6 +925,9 @@ reviews. Googlers can read more about this at go/gwsq-gerrit.
 
 <histogram name="Translate.UndisplayableLanguage" enum="LanguageName"
     expires_after="M81">
+  <obsolete>
+    Removed 01/09/2021. Not used anymore.
+  </obsolete>
   <owner>kenjibaheux@google.com</owner>
   <owner>chrome-language@google.com</owner>
   <summary>