Translate: adopt html lang attribute if valid value is provided

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 84e68fe966dce49dfb4caeaab5a99e6ac0ab2b7c..cf9804dd316ff086808365589f2baeb5b05f19a1 100644
--- a/chrome/renderer/translate/translate_helper.cc
+++ b/chrome/renderer/translate/translate_helper.cc
@@ -93,18 +93,28 @@ void TranslateHelper::PageCaptured(const string16& contents) {
   // language of the intended audience (a distinction really only
   // relevant for things like langauge textbooks).  This distinction
   // shouldn't affect translation.
-  WebDocument document = GetMainFrame()->document();
+  WebFrame* main_frame = GetMainFrame();
+  if (!main_frame)
+    return;
+  WebDocument document = main_frame->document();
   std::string content_language = document.contentLanguage().utf8();
+  WebElement html_element = document.documentElement();
+  std::string html_lang;
+  // |html_element| can be null element, e.g. in
+  // BrowserTest.WindowOpenClose.
+  if (!html_element.isNull())
+    html_lang = html_element.getAttribute("lang").utf8();
   std::string cld_language;
   bool is_cld_reliable;
   std::string language = DeterminePageLanguage(
-      content_language, contents, &cld_language, &is_cld_reliable);
+      content_language, html_lang, contents, &cld_language, &is_cld_reliable);
 
   if (language.empty())
     return;
 
   language_determined_time_ = base::TimeTicks::Now();
 
+  // TODO(toyoshim): Add |html_lang| to LanguageDetectionDetails.
   GURL url(document.url());
   LanguageDetectionDetails details;
   details.time = base::Time::Now();
@@ -319,7 +329,20 @@ void TranslateHelper::ResetInvalidLanguageCode(std::string* code) {
 }
 
 // static
+void TranslateHelper::ApplyLanguageCodeCorrection(std::string* code) {
+  // Correct well-known format errors.
+  CorrectLanguageCodeTypo(code);
+
+  // Convert language code synonym firstly because sometime synonym code is in
+  // invalid format, e.g. 'fil'. After validation, such a 3 characters language
+  // gets converted to an empty string.
+  ConvertLanguageCodeSynonym(code);
+  ResetInvalidLanguageCode(code);
+}
+
+// static
 std::string TranslateHelper::DeterminePageLanguage(const std::string& code,
+                                                   const std::string& html_lang,
                                                    const string16& contents,
                                                    std::string* cld_language_p,
                                                    bool* is_cld_reliable_p) {
@@ -337,17 +360,27 @@ std::string TranslateHelper::DeterminePageLanguage(const std::string& code,
   ConvertLanguageCodeSynonym(&cld_language);
 #endif  // defined(ENABLE_LANGUAGE_DETECTION)
 
-  // Correct well-known format errors.
-  std::string language = code;
-  CorrectLanguageCodeTypo(&language);
+  // Check if html lang attribute is valid.
+  std::string modified_html_lang;
+  if (!html_lang.empty()) {
+    modified_html_lang = html_lang;
+    ApplyLanguageCodeCorrection(&modified_html_lang);
+    TranslateHelperMetrics::ReportHtmlLang(html_lang, modified_html_lang);
+    VLOG(9) << "html lang based language code: " << modified_html_lang;
+  }
 
-  // Convert language code synonym firstly because sometime synonym code is in
-  // invalid format, e.g. 'fil'. After validation, such a 3 characters language
-  // gets converted to an empty string.
-  ConvertLanguageCodeSynonym(&language);
-  ResetInvalidLanguageCode(&language);
+  // Check if Content-Language is valid.
+  std::string modified_code;
+  if (!code.empty()) {
+    modified_code = code;
+    ApplyLanguageCodeCorrection(&modified_code);
+    TranslateHelperMetrics::ReportContentLanguage(code, modified_code);
+  }
 
-  TranslateHelperMetrics::ReportContentLanguage(code, language);
+  // Adopt |modified_html_lang| if it is valid. Otherwise, adopt
+  // |modified_code|.
+  std::string language = modified_html_lang.empty() ? modified_code :
+                                                      modified_html_lang;
 
 #if defined(ENABLE_LANGUAGE_DETECTION)
   // If |language| is empty, just use CLD result even though it might be
@@ -433,7 +466,8 @@ void TranslateHelper::OnTranslatePage(int page_id,
                                       const std::string& translate_script,
                                       const std::string& source_lang,
                                       const std::string& target_lang) {
-  if (render_view()->GetPageId() != page_id)
+  WebFrame* main_frame = GetMainFrame();
+  if (!main_frame || render_view()->GetPageId() != page_id)
     return;  // We navigated away, nothing to do.
 
   if (translation_pending_ && page_id == page_id_ &&
@@ -457,7 +491,7 @@ void TranslateHelper::OnTranslatePage(int page_id,
   TranslateHelperMetrics::ReportUserActionDuration(language_determined_time_,
                                                    base::TimeTicks::Now());
 
-  GURL url(GetMainFrame()->document().url());
+  GURL url(main_frame->document().url());
   TranslateHelperMetrics::ReportPageScheme(url.scheme());
 
   if (!IsTranslateLibAvailable()) {
@@ -590,12 +624,10 @@ void TranslateHelper::NotifyBrowserTranslationFailed(
 
 WebFrame* TranslateHelper::GetMainFrame() {
   WebView* web_view = render_view()->GetWebView();
-  if (!web_view) {
-    // When the WebView is going away, the render view should have called
-    // CancelPendingTranslation() which should have stopped any pending work, so
-    // that case should not happen.
-    NOTREACHED();
+
+  // When the tab is going to be closed, the web_view can be NULL.
+  if (!web_view)
     return NULL;
-  }
+
   return web_view->mainFrame();
 }