Allos IsUsbConnected() to be overridden

Virtual platforms may not have USB, but they can still use the SDCard
method. Allow the USB connection status to be faked so the 120s timeout
is not applied.

Bug: 155222461
Change-Id: I67f32c2b5b0941d5e3c0675dad23fe7121e5af86
diff --git a/recovery_ui/include/recovery_ui/ui.h b/recovery_ui/include/recovery_ui/ui.h
index 08ec1d7..512732f 100644
--- a/recovery_ui/include/recovery_ui/ui.h
+++ b/recovery_ui/include/recovery_ui/ui.h
@@ -192,6 +192,8 @@
     return key_interrupted_;
   }
 
+  virtual bool IsUsbConnected();
+
  protected:
   void EnqueueKey(int key_code);
 
@@ -226,8 +228,6 @@
   void ProcessKey(int key_code, int updown);
   void TimeKey(int key_code, int count);
 
-  bool IsUsbConnected();
-
   bool InitScreensaver();
   void SetScreensaverState(ScreensaverState state);