Device owns the RecoveryUI instance.

Test: mmma -j bootable/recovery
Test: Build and boot into recovery, w/ and w/o enabling quiescent mode
      respectively.
Change-Id: I5d9bb945a6c3c9a3b96199fa0c8071a2f91339a0

screen_ui.cpp

@@ -751,7 +751,7 @@ bool ScreenRecoveryUI::Init(const std::string& locale) {
   return true;
 }
 
-std::string ScreenRecoveryUI::GetLocale() {
+std::string ScreenRecoveryUI::GetLocale() const {
   return locale_;
 }