GetTargetLanguage() returns the UI language if it's supported by the

translation service or the first supported language in the accepted languages
list. If there is no such language, returns "".

BUG=37328
TEST=1. browser_tests: TranslateManagerTest.TranslateAcceptLanguage and TranslateManagerTest.UnsupportedUILanguag
2. a. Start Chrome in the UI language that's unsupported by the translation
service (like Amharic). On Windows, "chrome --lang=am". On Linux, 'LANGUAGE=am chrome' with Amharic locale installed. 
   b. add a language supported by the translation service to the Accept-Languages list (e.g Italian and Spanish). 
  c. When navigating to a page in a third language (e.g. French), it should offer to translate to the first supported language in the Accept-Language list (Italian in the scenario).

Contributed by dfilimon@google.com

Review URL: http://codereview.chromium.org/7327008

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@92162 0039d316-1c4b-4281-b951-d872f2087c98

3 files changed, 51 insertions, 9 deletions

diff --git a/chrome/browser/translate/translate_manager.cc b/chrome/browser/translate/translate_manager.cc
index 0888ba5..1fcf475 100644
--- a/chrome/browser/translate/translate_manager.cc
+++ b/chrome/browser/translate/translate_manager.cc
@@ -459,7 +459,7 @@ void TranslateManager::InitiateTranslation(TabContents* tab,
   if (GetTranslateInfoBarDelegate(tab))
     return;
 
-  std::string target_lang = GetTargetLanguage();
+  std::string target_lang = GetTargetLanguage(prefs);
   std::string language_code = GetLanguageCode(page_lang);
   // Nothing to do if either the language Chrome is in or the language of the
   // page is not supported by the translation server.
@@ -761,10 +761,27 @@ void TranslateManager::ShowInfoBar(TabContents* tab,
 }
 
 // static
-std::string TranslateManager::GetTargetLanguage() {
-  std::string target_lang =
-      GetLanguageCode(g_browser_process->GetApplicationLocale());
-  return IsSupportedLanguage(target_lang) ? target_lang : std::string();
+std::string TranslateManager::GetTargetLanguage(PrefService* prefs) {
+  std::string ui_lang =
+    GetLanguageCode(g_browser_process->GetApplicationLocale());
+  if (IsSupportedLanguage(ui_lang))
+    return ui_lang;
+
+  // Getting the accepted languages list
+  std::string accept_langs_str = prefs->GetString(prefs::kAcceptLanguages);
+
+  std::vector<std::string> accept_langs_list;
+  base::SplitString(accept_langs_str, ',', &accept_langs_list);
+
+  // Will translate to the first supported language on the Accepted Language
+  // list or not at all if no such candidate exists
+  std::vector<std::string>::iterator iter;
+  for (iter = accept_langs_list.begin();
+       iter != accept_langs_list.end(); ++iter) {
+    if (IsSupportedLanguage(GetLanguageCode(*iter)))
+      return *iter;
+  }
+  return std::string();
 }
 
 // static
diff --git a/chrome/browser/translate/translate_manager.h b/chrome/browser/translate/translate_manager.h
index ab710f2..2537d8e 100644
--- a/chrome/browser/translate/translate_manager.h
+++ b/chrome/browser/translate/translate_manager.h
@@ -168,10 +168,13 @@ class TranslateManager : public NotificationObserver,
   // translate infobar is showing, it just replaces it with the new one.
   void ShowInfoBar(TabContents* tab, TranslateInfoBarDelegate* infobar);
 
-  // Returns the language to translate to, which is the language the UI is
-  // configured in.  Returns an empty string if that language is not supported
-  // by the translation service.
-  static std::string GetTargetLanguage();
+  // Returns the language to translate to. The language returned is the
+  // first language found in the following list that is supported by the
+  // translation service:
+  //     the UI language
+  //     the accept-language list
+  // If no language is found then an empty string is returned.
+  static std::string GetTargetLanguage(PrefService* prefs);
 
   // Returns the translate info bar showing in |tab| or NULL if none is showing.
   static TranslateInfoBarDelegate* GetTranslateInfoBarDelegate(
diff --git a/chrome/browser/translate/translate_manager_browsertest.cc b/chrome/browser/translate/translate_manager_browsertest.cc
index 5e9cf9e..3028561 100644
--- a/chrome/browser/translate/translate_manager_browsertest.cc
+++ b/chrome/browser/translate/translate_manager_browsertest.cc
@@ -873,6 +873,10 @@ TEST_F(TranslateManagerTest, UnsupportedUILanguage) {
   std::string original_lang = browser_process->GetApplicationLocale();
   browser_process->SetApplicationLocale("qbz");
 
+  // Make sure that the accept language list only contains unsupported languages
+  PrefService* prefs = contents()->profile()->GetPrefs();
+  prefs->SetString(prefs::kAcceptLanguages, "qbz");
+
   // Simulate navigating to a page in a language supported by the translate
   // server.
   SimulateNavigation(GURL("http://www.google.com"), "en", true);
@@ -883,6 +887,24 @@ TEST_F(TranslateManagerTest, UnsupportedUILanguage) {
   browser_process->SetApplicationLocale(original_lang);
 }
 
+// Tests that the first supported accept language is selected
+TEST_F(TranslateManagerTest, TranslateAcceptLanguage) {
+  // Set locate to non-existant language
+  TestingBrowserProcess* browser_process = testing_browser_process_.get();
+  std::string original_lang = browser_process->GetApplicationLocale();
+  browser_process->SetApplicationLocale("qbz");
+
+  // Set Qbz and French as the only accepted languages
+  PrefService* prefs = contents()->profile()->GetPrefs();
+  prefs->SetString(prefs::kAcceptLanguages, "qbz,fr");
+
+  // Go to a German page
+  SimulateNavigation(GURL("http://google.de"), "de", true);
+
+  // Expect the infobar to pop up
+  EXPECT_TRUE(GetTranslateInfoBar() != NULL);
+}
+
 // Tests that the translate enabled preference is honored.
 TEST_F(TranslateManagerTest, TranslateEnabledPref) {
   // Make sure the pref allows translate.