Prevent apps from displaying over Settings

Specifically, the DrawOverlayDetails fragment only.

Bug: 36070413
Test: make RunSettingsRoboTests -j100
Change-Id: I0069f0cacf8c963c8c6878dc89a32b205983a568

src/com/android/settings/applications/DrawOverlayDetails.java

@@ -36,6 +36,7 @@ import com.android.internal.logging.nano.MetricsProto.MetricsEvent;
 import com.android.settings.R;
 import com.android.settings.applications.AppStateAppOpsBridge.PermissionState;
 import com.android.settings.applications.AppStateOverlayBridge.OverlayState;
+import com.android.settings.core.TouchOverlayManager;
 import com.android.settings.overlay.FeatureFactory;
 import com.android.settingslib.applications.ApplicationsState.AppEntry;
 
@@ -61,6 +62,8 @@ public class DrawOverlayDetails extends AppInfoWithHeader implements OnPreferenc
     private Intent mSettingsIntent;
     private OverlayState mOverlayState;
 
+    private TouchOverlayManager mTouchOverlayManager;
+
     @Override
     public void onCreate(Bundle savedInstanceState) {
         super.onCreate(savedInstanceState);
@@ -68,6 +71,7 @@ public class DrawOverlayDetails extends AppInfoWithHeader implements OnPreferenc
         Context context = getActivity();
         mOverlayBridge = new AppStateOverlayBridge(context, mState, null);
         mAppOpsManager = (AppOpsManager) context.getSystemService(Context.APP_OPS_SERVICE);
+        mTouchOverlayManager = new TouchOverlayManager(context);
 
         // find preferences
         addPreferencesFromResource(R.xml.app_ops_permissions_details);
@@ -89,6 +93,20 @@ public class DrawOverlayDetails extends AppInfoWithHeader implements OnPreferenc
                 .setAction(Settings.ACTION_MANAGE_OVERLAY_PERMISSION);
     }
 
+    @Override
+    public void onStart() {
+        super.onStart();
+
+        mTouchOverlayManager.setOverlayAllowed(false);
+    }
+
+    @Override
+    public void onStop() {
+        super.onStop();
+
+        mTouchOverlayManager.setOverlayAllowed(true);
+    }
+
     @Override
     public void onDestroy() {
         super.onDestroy();

src/com/android/settings/core/TouchOverlayManager.java

@@ -0,0 +1,40 @@
+/*
+ * Copyright (C) 2017 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License
+ */
+
+package com.android.settings.core;
+
+import android.app.AppOpsManager;
+import android.content.Context;
+import android.os.Binder;
+import android.os.IBinder;
+
+public class TouchOverlayManager {
+
+    private final Context mContext;
+    private final IBinder mToken = new Binder();
+
+    public TouchOverlayManager(Context context) {
+        mContext = context;
+    }
+
+    public void setOverlayAllowed(boolean allowed) {
+        final AppOpsManager aom = mContext.getSystemService(AppOpsManager.class);
+        if (aom != null) {
+            aom.setUserRestriction(AppOpsManager.OP_SYSTEM_ALERT_WINDOW, !allowed, mToken);
+            aom.setUserRestriction(AppOpsManager.OP_TOAST_WINDOW, !allowed, mToken);
+        }
+    }
+}

tests/robotests/src/com/android/settings/applications/DrawOverlayDetailsTest.java

@@ -19,10 +19,11 @@ package com.android.settings.applications;
 import android.content.Context;
 
 import com.android.internal.logging.nano.MetricsProto;
-import com.android.internal.telephony.SmsUsageMonitor;
 import com.android.settings.SettingsRobolectricTestRunner;
 import com.android.settings.TestConfig;
+import com.android.settings.core.TouchOverlayManager;
 import com.android.settings.testutils.FakeFeatureFactory;
+import com.android.settings.testutils.shadow.ShadowPreferenceFragment;
 
 import org.junit.Before;
 import org.junit.Test;
@@ -32,6 +33,7 @@ import org.mockito.Mock;
 import org.mockito.MockitoAnnotations;
 import org.robolectric.annotation.Config;
 import org.robolectric.shadows.ShadowApplication;
+import org.robolectric.util.ReflectionHelpers;
 
 import static org.mockito.Matchers.any;
 import static org.mockito.Matchers.eq;
@@ -47,17 +49,22 @@ public class DrawOverlayDetailsTest {
     private FakeFeatureFactory mFeatureFactory;
     private DrawOverlayDetails mFragment;
 
+    @Mock
+    private TouchOverlayManager mTouchOverlayManager;
+
     @Before
     public void setUp() {
         MockitoAnnotations.initMocks(this);
         FakeFeatureFactory.setupForTest(mContext);
         mFeatureFactory = (FakeFeatureFactory) FakeFeatureFactory.getFactory(mContext);
+
         mFragment = new DrawOverlayDetails();
-        mFragment.onAttach(ShadowApplication.getInstance().getApplicationContext());
+        ReflectionHelpers.setField(mFragment, "mTouchOverlayManager", mTouchOverlayManager);
     }
 
     @Test
     public void logSpecialPermissionChange() {
+        mFragment.onAttach(ShadowApplication.getInstance().getApplicationContext());
         mFragment.logSpecialPermissionChange(true, "app");
         verify(mFeatureFactory.metricsFeatureProvider).action(any(Context.class),
                 eq(MetricsProto.MetricsEvent.APP_SPECIAL_PERMISSION_APPDRAW_ALLOW), eq("app"));
@@ -66,4 +73,18 @@ public class DrawOverlayDetailsTest {
         verify(mFeatureFactory.metricsFeatureProvider).action(any(Context.class),
                 eq(MetricsProto.MetricsEvent.APP_SPECIAL_PERMISSION_APPDRAW_DENY), eq("app"));
     }
+
+    @Test
+    @Config(shadows = ShadowPreferenceFragment.class)
+    public void onStart_disableOverlay() {
+        mFragment.onStart();
+        verify(mTouchOverlayManager).setOverlayAllowed(false);
+    }
+
+    @Test
+    @Config(shadows = ShadowPreferenceFragment.class)
+    public void onStop_enableOverlay() {
+        mFragment.onStop();
+        verify(mTouchOverlayManager).setOverlayAllowed(true);
+    }
 }

tests/robotests/src/com/android/settings/testutils/shadow/ShadowPreferenceFragment.java

@@ -0,0 +1,35 @@
+/*
+ * Copyright (C) 2017 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License
+ */
+
+package com.android.settings.testutils.shadow;
+
+import android.support.v14.preference.PreferenceFragment;
+import org.robolectric.annotation.Implementation;
+import org.robolectric.annotation.Implements;
+
+@Implements(PreferenceFragment.class)
+public class ShadowPreferenceFragment {
+
+    @Implementation
+    public void onStart() {
+        // No-op.
+    }
+
+    @Implementation
+    public void onStop() {
+        // No-op.
+    }
+}