Clean up ShadowUserManager.

Remove usages of the custom shadow where they are no longer needed and
remove the mock instance pattern in favor of adding users via the
Robolectric ShadowUserManager's API.

Bug: 137316669

Test: RunCarSettingsRoboTests

Change-Id: I33c2e07002fa8b558751e2be6c17b5bb616e9f50
diff --git a/tests/robotests/src/com/android/car/settings/applications/ApplicationDetailsFragmentTest.java b/tests/robotests/src/com/android/car/settings/applications/ApplicationDetailsFragmentTest.java
index 8136b17..8c9ac2a 100644
--- a/tests/robotests/src/com/android/car/settings/applications/ApplicationDetailsFragmentTest.java
+++ b/tests/robotests/src/com/android/car/settings/applications/ApplicationDetailsFragmentTest.java
@@ -18,7 +18,6 @@
 
 import static com.google.common.truth.Truth.assertThat;
 
-import static org.mockito.Mockito.mock;
 import static org.mockito.Mockito.when;
 
 import android.app.Activity;
@@ -34,7 +33,6 @@
 import android.content.pm.PackageManager;
 import android.content.pm.ResolveInfo;
 import android.content.pm.Signature;
-import android.content.pm.UserInfo;
 import android.os.Bundle;
 import android.os.Handler;
 import android.os.UserHandle;
@@ -103,17 +101,15 @@
         MockitoAnnotations.initMocks(this);
         ShadowCarUserManagerHelper.setMockInstance(mCarUserManagerHelper);
         int userId = UserHandle.myUserId();
-        UserInfo userInfo = new UserInfo();
-        userInfo.id = userId;
-        when(mCarUserManagerHelper.getCurrentProcessUserId()).thenReturn(userId);
-        when(mCarUserManagerHelper.getAllUsers()).thenReturn(Collections.singletonList(userInfo));
-        UserManager mockUserManager = mock(UserManager.class);
-        when(mockUserManager.getUserInfo(userId)).thenReturn(userInfo);
-        ShadowUserManager.setInstance(mockUserManager);
 
         mContext = RuntimeEnvironment.application;
+        getShadowUserManager().addUser(userId, "userName", /* flags= */ 0);
         getShadowUserManager().addProfile(userId, userId, "profileName", /* profileFlags= */ 0);
 
+        when(mCarUserManagerHelper.getCurrentProcessUserId()).thenReturn(userId);
+        when(mCarUserManagerHelper.getAllUsers()).thenReturn(
+                Collections.singletonList(UserManager.get(mContext).getUserInfo(userId)));
+
         mActivity = new TestActivity();
         mController = ActivityController.of(mActivity);
         mController.create();