Fixed mUserId_shouldDeriveUidFromMainCaller test case fail

- getApplicationContext() return null in some test cases.
- Add null checking to avoid the NPE failed.

Fixes: 263542897
Test: make RunSettingsRoboTests -j ROBOTEST_FILTER=com.android.settings.applications
Change-Id: I374b5bbf8911bd6d4eb992e0fa7b1a67c3d16a91

src/com/android/settings/SettingsApplication.java

@@ -43,7 +43,11 @@ public class SettingsApplication extends Application {
     @Override
     public void onCreate() {
         super.onCreate();
-        ElapsedTimeUtils.assignSuwFinishedTimeStamp(this.getApplicationContext());
+
+        // Add null checking to avoid test case failed.
+        if (getApplicationContext() != null) {
+            ElapsedTimeUtils.assignSuwFinishedTimeStamp(getApplicationContext());
+        }
 
         // Set Spa environment.
         setSpaEnvironment();