PiP: Safeguard in calling on menu view in case it's not created.

In case SystemUI crashes, there is a possibility that we can call on
showMenu() upon SysUI restart without the menu instance created. We
should at least not crash SysUI again for this.

Bug: 173683353
Test: None
Change-Id: I67c11ffaf9f7e6972cc4b005f07f8fc6897ac5c1

libs/WindowManager/Shell/src/com/android/wm/shell/pip/phone/PipMenuActivityController.java

@@ -239,7 +239,9 @@ public class PipMenuActivityController {
                     + " callers=\n" + Debug.getCallers(5, "    "));
         }
 
-        maybeCreateSyncApplier();
+        if (!maybeCreateSyncApplier()) {
+            return;
+        }
 
         mPipMenuView.showMenu(menuState, stackBounds, allowMenuTimeout, willResizeMenu, withDelay,
                 showResizeHandle);