screen_ui: Drop the parameter in CheckBackgroundTextImages.

ScreenRecoveryUI already has the info in locale_.

Also when showing "Current locale: X/Y" on screen, use 1-based index for
X, so that we have 1 <= X <= Y.

Test: Build anf flash recovery image on aosp_bullhead-userdebug. Choose
      `Run locale test` from UI.
Change-Id: I5dd4de82e63890ddf755f4e23cd2290ad5d50ece
diff --git a/recovery.cpp b/recovery.cpp
index 01dce07..6aceb2d 100644
--- a/recovery.cpp
+++ b/recovery.cpp
@@ -897,7 +897,7 @@
 
       case Device::RUN_LOCALE_TEST: {
         ScreenRecoveryUI* screen_ui = static_cast<ScreenRecoveryUI*>(ui);
-        screen_ui->CheckBackgroundTextImages(screen_ui->GetLocale());
+        screen_ui->CheckBackgroundTextImages();
         break;
       }
       case Device::MOUNT_SYSTEM:
diff --git a/screen_ui.cpp b/screen_ui.cpp
index 4a1a5b9..90e0e30 100644
--- a/screen_ui.cpp
+++ b/screen_ui.cpp
@@ -372,7 +372,7 @@
   std::string header = "Show background text image";
   text_y += DrawTextLine(text_x, text_y, header, true);
   std::string locale_selection = android::base::StringPrintf(
-      "Current locale: %s, %zu/%zu", locales_entries[sel].c_str(), sel, locales_entries.size());
+      "Current locale: %s, %zu/%zu", locales_entries[sel].c_str(), sel + 1, locales_entries.size());
   // clang-format off
   std::vector<std::string> instruction = {
     locale_selection,
@@ -395,13 +395,14 @@
   pthread_mutex_unlock(&updateMutex);
 }
 
-void ScreenRecoveryUI::CheckBackgroundTextImages(const std::string& saved_locale) {
+void ScreenRecoveryUI::CheckBackgroundTextImages() {
   // Load a list of locales embedded in one of the resource files.
   std::vector<std::string> locales_entries = get_locales_in_png("installing_text");
   if (locales_entries.empty()) {
     Print("Failed to load locales from the resource files\n");
     return;
   }
+  std::string saved_locale = locale_;
   size_t selected = 0;
   SelectAndShowBackgroundText(locales_entries, selected);
 
diff --git a/screen_ui.h b/screen_ui.h
index 3e391be..d4923f5 100644
--- a/screen_ui.h
+++ b/screen_ui.h
@@ -148,9 +148,9 @@
 
   void SetColor(UIElement e) const;
 
-  // Check the background text image. Use volume up/down button to cycle through the locales
-  // embedded in the png file, and power button to go back to recovery main menu.
-  void CheckBackgroundTextImages(const std::string& saved_locale);
+  // Checks the background text image, for debugging purpose. It iterates the locales embedded in
+  // the on-device resource files and shows the localized text, for manual inspection.
+  void CheckBackgroundTextImages();
 
  protected:
   // The margin that we don't want to use for showing texts (e.g. round screen, or screen with