Add a stub recovery UI.

This allows recovery to work on devices without screen.
The stub recovery UI does nothing except print to stdout.

Test: write 'recovery\n--wipe_data\n--reason=wipe_data_from_ota\n'
      to misc and boot to recovery on a device without screen.
Bug: 33175036

Change-Id: Icde698aa2e2e29f4b3d0532dfd3c6a939ac2bc63
diff --git a/tests/component/verifier_test.cpp b/tests/component/verifier_test.cpp
index 60a78f5..33aadb3 100644
--- a/tests/component/verifier_test.cpp
+++ b/tests/component/verifier_test.cpp
@@ -40,7 +40,7 @@
 RecoveryUI* ui = NULL;
 
 class MockUI : public RecoveryUI {
-    void Init() { }
+    bool Init() { return true; }
     void SetStage(int, int) { }
     void SetLocale(const char*) { }
     void SetBackground(Icon /*icon*/) { }