a little code cleanup for translate infobars

- use index of selected language menu item (which corresponds to index in array of languages) to check if selection has changed; was retrieving, converting and comparing text, which is more expensive and slower
- only call backend to translate when source and target languages are different

BUG=31297
TEST=verify that selection of languages in translate infobars still work as expected.
Review URL: http://codereview.chromium.org/563018

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@37979 0039d316-1c4b-4281-b951-d872f2087c98

3 files changed, 17 insertions, 7 deletions

diff --git a/chrome/browser/translate/translate_infobars_delegates.cc b/chrome/browser/translate/translate_infobars_delegates.cc
index 3dba0ca..7bf2a4f 100644
--- a/chrome/browser/translate/translate_infobars_delegates.cc
+++ b/chrome/browser/translate/translate_infobars_delegates.cc
@@ -53,7 +53,8 @@ void TranslateInfoBarDelegate::GetAvailableTargetLanguages(
 }
 
 void TranslateInfoBarDelegate::Translate() {
-  tab_contents_->TranslatePage(original_lang_code(), target_lang_code());
+  if (original_lang_index_ != target_lang_index_)
+    tab_contents_->TranslatePage(original_lang_code(), target_lang_code());
 }
 
 bool TranslateInfoBarDelegate::IsLanguageBlacklisted() {
diff --git a/chrome/browser/translate/translate_infobars_delegates.h b/chrome/browser/translate/translate_infobars_delegates.h
index 18416c4..5b10f3f 100644
--- a/chrome/browser/translate/translate_infobars_delegates.h
+++ b/chrome/browser/translate/translate_infobars_delegates.h
@@ -28,6 +28,12 @@ class TranslateInfoBarDelegate : public InfoBarDelegate {
   virtual bool ShouldAlwaysTranslate();
   virtual void ToggleAlwaysTranslate();
 
+  int original_lang_index() const {
+    return original_lang_index_;
+  }
+  int target_lang_index() const {
+    return target_lang_index_;
+  }
   const std::string& original_lang_code() const {
     return supported_languages_[original_lang_index_];
   }
diff --git a/chrome/browser/views/infobars/translate_infobars.cc b/chrome/browser/views/infobars/translate_infobars.cc
index c65bea4..d20d844 100644
--- a/chrome/browser/views/infobars/translate_infobars.cc
+++ b/chrome/browser/views/infobars/translate_infobars.cc
@@ -455,15 +455,18 @@ gfx::Point TranslateInfoBar::DetermineMenuPositionAndAlignment(
 void TranslateInfoBar::OnLanguageModified(views::MenuButton* menu_button,
     int new_language_index) {
   // Only proceed if a different language has been selected.
-  string16 new_language = TranslateInfoBarDelegate::GetDisplayNameForLocale(
-      GetDelegate()->GetLocaleFromIndex(new_language_index));
-  if (new_language == WideToUTF16(menu_button->text()))
-    return;
-  if (menu_button == original_language_menu_button_)
+  if (menu_button == original_language_menu_button_) {
+    if (new_language_index == GetDelegate()->original_lang_index())
+      return;
     GetDelegate()->ModifyOriginalLanguage(new_language_index);
-  else
+  } else {
+    if (new_language_index == GetDelegate()->target_lang_index())
+      return;
     GetDelegate()->ModifyTargetLanguage(new_language_index);
+  }
 
+  string16 new_language = TranslateInfoBarDelegate::GetDisplayNameForLocale(
+      GetDelegate()->GetLocaleFromIndex(new_language_index));
   menu_button->SetText(UTF16ToWideHack(new_language));
   menu_button->ClearMaxTextSize();
   menu_button->SizeToPreferredSize();