Add a new option in recovery menu to test the background texts

Add a new option "Run locale test" to check the background text
images (i.e. texts for "erasing", "error", "no_command" and "installing"
with different locales.)

Use volume up/down button to cycle through all the locales embedded in
the png file, and power button to go back to recovery main menu.

Test: Run locale test with bullhead.
Change-Id: Ib16e119f372110cdb5e611ef497b0f9b9b418f51
diff --git a/recovery.cpp b/recovery.cpp
index d037b79..076b449 100644
--- a/recovery.cpp
+++ b/recovery.cpp
@@ -1191,6 +1191,11 @@
         run_graphics_test();
         break;
 
+      case Device::RUN_LOCALE_TEST: {
+        ScreenRecoveryUI* screen_ui = static_cast<ScreenRecoveryUI*>(ui);
+        screen_ui->CheckBackgroundTextImages(locale);
+        break;
+      }
       case Device::MOUNT_SYSTEM:
         // For a system image built with the root directory (i.e. system_root_image == "true"), we
         // mount it to /system_root, and symlink /system to /system_root/system to make adb shell