Finish HomepageActivity when it's not the root of a task and not singleTask.

HomepageActivity should be the first activity in a task, or be launched
in singleTask mode. Finishing it will bring up the previous activity in
the task.

Fix: 297857732
Test: robotest
Change-Id: Iddcba1652060d755693dd20d0e350e3d6c1ae138

src/com/android/settings/homepage/SettingsHomepageActivity.java

@@ -183,6 +183,12 @@ public class SettingsHomepageActivity extends FragmentActivity implements
     protected void onCreate(Bundle savedInstanceState) {
         super.onCreate(savedInstanceState);
 
+        if (!isTaskRoot() && !isSingleTask()) {
+            Log.i(TAG, "Not task root nor single task, finish");
+            finish();
+            return;
+        }
+
         mIsEmbeddingActivityEnabled = ActivityEmbeddingUtils.isEmbeddingActivityEnabled(this);
         if (mIsEmbeddingActivityEnabled) {
             final UserManager um = getSystemService(UserManager.class);
@@ -308,6 +314,12 @@ public class SettingsHomepageActivity extends FragmentActivity implements
         updateHomepageUI();
     }
 
+    private boolean isSingleTask() {
+        ActivityInfo info = getIntent().resolveActivityInfo(getPackageManager(),
+                PackageManager.MATCH_DEFAULT_ONLY);
+        return info.launchMode == ActivityInfo.LAUNCH_SINGLE_TASK;
+    }
+
     private void updateSplitLayout() {
         if (!mIsEmbeddingActivityEnabled) {
             return;

tests/robotests/src/com/android/settings/homepage/SettingsHomepageActivityTest.java

@@ -29,6 +29,7 @@ import static org.mockito.ArgumentMatchers.anyString;
 import static org.mockito.ArgumentMatchers.eq;
 import static org.mockito.Mockito.doReturn;
 import static org.mockito.Mockito.mock;
+import static org.mockito.Mockito.never;
 import static org.mockito.Mockito.spy;
 import static org.mockito.Mockito.verify;
 import static org.mockito.Mockito.when;
@@ -210,6 +211,28 @@ public class SettingsHomepageActivityTest {
                 & SYSTEM_FLAG_HIDE_NON_SYSTEM_OVERLAY_WINDOWS).isEqualTo(0);
     }
 
+    @Test
+    public void onCreate_notTaskRoot_shouldFinishActivity() {
+        SettingsHomepageActivity activity =
+                spy(Robolectric.buildActivity(SettingsHomepageActivity.class).get());
+        doReturn(false).when(activity).isTaskRoot();
+
+        activity.onCreate(/* savedInstanceState */ null);
+
+        verify(activity).finish();
+    }
+
+    @Test
+    public void onCreate_singleTaskActivity_shouldNotFinishActivity() {
+        SettingsHomepageActivity activity =
+                spy(Robolectric.buildActivity(DeepLinkHomepageActivity.class).get());
+        doReturn(false).when(activity).isTaskRoot();
+
+        activity.onCreate(/* savedInstanceState */ null);
+
+        verify(activity, never()).finish();
+    }
+
     /** This test is for large screen devices Activity embedding. */
     @Test
     @Config(shadows = ShadowActivityEmbeddingUtils.class)