Allow showBouncer to be overridden in subclasses

Bug: 28759481
Change-Id: I6c33e47f46c46a808d1e945f19a266094fafe56f
(cherry picked from commit 75a8c0cad9a039fbc713e715f79106c524e9de31)

packages/SystemUI/src/com/android/systemui/statusbar/phone/PhoneStatusBar.java

@@ -4223,7 +4223,7 @@ public class PhoneStatusBar extends BaseStatusBar implements DemoMode,
         return false;
     }
 
-    private void showBouncer() {
+    protected void showBouncer() {
         if (mState == StatusBarState.KEYGUARD || mState == StatusBarState.SHADE_LOCKED) {
             mWaitingForKeyguardExit = mStatusBarKeyguardViewManager.isShowing();
             mStatusBarKeyguardViewManager.dismiss();