Add a setting for allowing overlays on Settings app

In the past, we allowed non system overlays on user-debug rom.
Acoording to the user-debug guildline, we should not have differnt
behavior between the user build and user debug rom.

To maintain the consistency between user and user debug rom,
We're creating a new developer setting for allowing non-system overlay on
Settings. By default, we don't allow any non-system app overlays on
Settings app unless user turns it on explictly.

Test: Run robotest. Turn on setting, see the overlays on Settings.
Turn off setting, do not see the overlays on Settings.
Fix: 144989059

Change-Id: I87f00a2eda91de003c6e542e7ec45a066f46fbf7

res/values/strings.xml

@@ -12094,4 +12094,9 @@
 
     <!-- Developer settings: app freezer title [CHAR LIMIT=50]-->
     <string name="cached_apps_freezer">Suspend execution for cached apps</string>
+
+    <!-- Title for allowing screen overlays on Settings app. [CHAR LIMIT=50]-->
+    <string name="overlay_settings_title">Allow screen overlays on Settings</string>
+    <!-- Summary for allowing screen overlays on Settings app. [CHAR LIMIT=NONE]-->
+    <string name="overlay_settings_summary">Allow apps that can display over other apps to overlay Settings screens</string>
 </resources>

res/xml/development_settings.xml

@@ -251,6 +251,11 @@
             android:title="@string/show_refresh_rate"
             android:summary="@string/show_refresh_rate_summary" />
 
+        <SwitchPreference
+            android:key="overlay_settings"
+            android:title="@string/overlay_settings_title"
+            android:summary="@string/overlay_settings_summary" />
+
     </PreferenceCategory>
 
     <PreferenceCategory

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

@@ -22,7 +22,6 @@ import static androidx.lifecycle.Lifecycle.Event.ON_START;
 import static androidx.lifecycle.Lifecycle.Event.ON_STOP;
 
 import android.app.Activity;
-import android.os.Build;
 import android.view.Window;
 import android.view.WindowManager;
 
@@ -30,6 +29,8 @@ import androidx.annotation.VisibleForTesting;
 import androidx.lifecycle.LifecycleObserver;
 import androidx.lifecycle.OnLifecycleEvent;
 
+import com.android.settings.development.OverlaySettingsPreferenceController;
+
 
 /**
  * A mixin that adds window flag to prevent non-system overlays showing on top of Settings
@@ -45,7 +46,7 @@ public class HideNonSystemOverlayMixin implements LifecycleObserver {
 
     @VisibleForTesting
     boolean isEnabled() {
-        return !Build.IS_DEBUGGABLE;
+        return !OverlaySettingsPreferenceController.isOverlaySettingsEnabled(mActivity);
     }
 
     @OnLifecycleEvent(ON_START)

src/com/android/settings/development/DevelopmentSettingsDashboardFragment.java

@@ -539,6 +539,7 @@ public class DevelopmentSettingsDashboardFragment extends RestrictedDashboardFra
         controllers.add(new BluetoothHDAudioPreferenceController(context, lifecycle,
                 bluetoothA2dpConfigStore, fragment));
         controllers.add(new SharedDataPreferenceController(context));
+        controllers.add(new OverlaySettingsPreferenceController(context));
 
         return controllers;
     }

src/com/android/settings/development/OverlaySettingsPreferenceController.java

@@ -0,0 +1,88 @@
+/*
+ * Copyright (C) 2020 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.development;
+
+import android.content.Context;
+import android.content.SharedPreferences;
+
+import androidx.annotation.VisibleForTesting;
+import androidx.preference.Preference;
+import androidx.preference.SwitchPreference;
+
+import com.android.settings.core.PreferenceControllerMixin;
+import com.android.settingslib.development.DeveloperOptionsPreferenceController;
+
+/**
+ * A controller helps enable or disable a developer setting which allows non system overlays on
+ * Settings app.
+ */
+public class OverlaySettingsPreferenceController extends DeveloperOptionsPreferenceController
+        implements Preference.OnPreferenceChangeListener, PreferenceControllerMixin {
+
+    public static final String SHARE_PERFS = "overlay_settings";
+    private static final String KEY_OVERLAY_SETTINGS = "overlay_settings";
+
+    public OverlaySettingsPreferenceController(Context context) {
+        super(context);
+    }
+
+    @Override
+    public boolean isAvailable() {
+        return true;
+    }
+
+    @Override
+    public String getPreferenceKey() {
+        return KEY_OVERLAY_SETTINGS;
+    }
+
+    @Override
+    public boolean onPreferenceChange(Preference preference, Object newValue) {
+        setOverlaySettingsEnabled(mContext, (Boolean) newValue);
+        return true;
+    }
+
+    @Override
+    public void updateState(Preference preference) {
+        ((SwitchPreference) preference).setChecked(isOverlaySettingsEnabled(mContext));
+    }
+
+    /**
+     * Check if this setting is enabled or not.
+     */
+    public static boolean isOverlaySettingsEnabled(Context context) {
+        final SharedPreferences editor = context.getSharedPreferences(SHARE_PERFS,
+                Context.MODE_PRIVATE);
+        return editor.getBoolean(SHARE_PERFS, false /* defValue */);
+    }
+
+    /**
+     * Enable this setting.
+     */
+    @VisibleForTesting
+    static void setOverlaySettingsEnabled(Context context, boolean enabled) {
+        final SharedPreferences editor = context.getSharedPreferences(SHARE_PERFS,
+                Context.MODE_PRIVATE);
+        editor.edit().putBoolean(SHARE_PERFS, enabled).apply();
+    }
+
+    @Override
+    protected void onDeveloperOptionsSwitchDisabled() {
+        super.onDeveloperOptionsSwitchDisabled();
+        setOverlaySettingsEnabled(mContext, false);
+    }
+}

tests/robotests/src/com/android/settings/core/HideNonSystemOverlayMixinTest.java

@@ -20,7 +20,8 @@ import static android.view.WindowManager.LayoutParams.SYSTEM_FLAG_HIDE_NON_SYSTE
 
 import static com.google.common.truth.Truth.assertThat;
 
-import android.os.Build;
+import android.content.Context;
+import android.content.SharedPreferences;
 import android.os.Bundle;
 import android.view.WindowManager;
 
@@ -28,6 +29,7 @@ import androidx.annotation.Nullable;
 import androidx.appcompat.app.AppCompatActivity;
 
 import com.android.settings.R;
+import com.android.settings.development.OverlaySettingsPreferenceController;
 
 import org.junit.Before;
 import org.junit.Test;
@@ -35,7 +37,6 @@ import org.junit.runner.RunWith;
 import org.robolectric.Robolectric;
 import org.robolectric.RobolectricTestRunner;
 import org.robolectric.android.controller.ActivityController;
-import org.robolectric.util.ReflectionHelpers;
 
 @RunWith(RobolectricTestRunner.class)
 public class HideNonSystemOverlayMixinTest {
@@ -69,17 +70,27 @@ public class HideNonSystemOverlayMixinTest {
     }
 
     @Test
-    public void isEnabled_debug_false() {
-        ReflectionHelpers.setStaticField(Build.class, "IS_DEBUGGABLE", true);
+    public void isEnabled_isAllowedOverlaySettings_returnFalse() {
+        mActivityController.setup();
+        final TestActivity activity = mActivityController.get();
+        final SharedPreferences editor = activity.getSharedPreferences(
+                OverlaySettingsPreferenceController.SHARE_PERFS,
+                Context.MODE_PRIVATE);
+        editor.edit().putBoolean(OverlaySettingsPreferenceController.SHARE_PERFS, true).apply();
 
-        assertThat(new HideNonSystemOverlayMixin(null).isEnabled()).isFalse();
+        assertThat(new HideNonSystemOverlayMixin(activity).isEnabled()).isFalse();
     }
 
     @Test
-    public void isEnabled_user_true() {
-        ReflectionHelpers.setStaticField(Build.class, "IS_DEBUGGABLE", false);
+    public void isEnabled_isNotAllowedOverlaySettings_returnTrue() {
+        mActivityController.setup();
+        TestActivity activity = mActivityController.get();
+        final SharedPreferences editor = activity.getSharedPreferences(
+                OverlaySettingsPreferenceController.SHARE_PERFS,
+                Context.MODE_PRIVATE);
+        editor.edit().putBoolean(OverlaySettingsPreferenceController.SHARE_PERFS, false).apply();
 
-        assertThat(new HideNonSystemOverlayMixin(null).isEnabled()).isTrue();
+        assertThat(new HideNonSystemOverlayMixin(activity).isEnabled()).isTrue();
     }
 
     public static class TestActivity extends AppCompatActivity {

tests/robotests/src/com/android/settings/development/OverlaySettingsPreferenceControllerTest.java

@@ -0,0 +1,120 @@
+/*
+ * Copyright (C) 2020 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.development;
+
+import static com.google.common.truth.Truth.assertThat;
+
+import android.content.Context;
+import android.content.SharedPreferences;
+
+import androidx.preference.SwitchPreference;
+
+import org.junit.Before;
+import org.junit.Test;
+import org.junit.runner.RunWith;
+import org.robolectric.RobolectricTestRunner;
+import org.robolectric.RuntimeEnvironment;
+
+@RunWith(RobolectricTestRunner.class)
+public class OverlaySettingsPreferenceControllerTest {
+
+    private Context mContext;
+    private SwitchPreference mPreference;
+    private OverlaySettingsPreferenceController mController;
+
+    @Before
+    public void setUp() {
+        mContext = RuntimeEnvironment.application;
+        mController = new OverlaySettingsPreferenceController(mContext);
+        mPreference = new SwitchPreference(mContext);
+    }
+
+    @Test
+    public void isAvailable_shouldReturnTrue() {
+        assertThat(mController.isAvailable()).isTrue();
+    }
+
+    @Test
+    public void updateState_isOverlaySettingsEnabled_shouldCheckPreference() {
+        OverlaySettingsPreferenceController.setOverlaySettingsEnabled(mContext, true);
+
+        mController.updateState(mPreference);
+
+        assertThat(mPreference.isChecked()).isTrue();
+    }
+
+    @Test
+    public void updateState_isOverlaySettingsDisabled_shouldUncheckPreference() {
+        OverlaySettingsPreferenceController.setOverlaySettingsEnabled(mContext, false);
+
+        mController.updateState(mPreference);
+
+        assertThat(mPreference.isChecked()).isFalse();
+    }
+
+    @Test
+    public void onPreferenceChange_preferenceChecked_shouldEnableSettings() {
+        mController.onPreferenceChange(mPreference, true);
+
+        assertThat(OverlaySettingsPreferenceController.isOverlaySettingsEnabled(mContext)).isTrue();
+    }
+
+    @Test
+    public void onPreferenceChange_preferenceUnchecked_shouldDisableSettings() {
+        mController.onPreferenceChange(mPreference, false);
+
+        assertThat(
+                OverlaySettingsPreferenceController.isOverlaySettingsEnabled(mContext)).isFalse();
+    }
+
+    @Test
+    public void isOverlaySettingsEnabled_sharePreferenceSetTrue_shouldReturnTrue() {
+        final SharedPreferences editor = mContext.getSharedPreferences(
+                OverlaySettingsPreferenceController.SHARE_PERFS,
+                Context.MODE_PRIVATE);
+        editor.edit().putBoolean(OverlaySettingsPreferenceController.SHARE_PERFS, true).apply();
+
+        assertThat(OverlaySettingsPreferenceController.isOverlaySettingsEnabled(mContext)).isTrue();
+    }
+
+    @Test
+    public void isOverlaySettingsEnabled_sharePreferenceSetFalse_shouldReturnFalse() {
+        final SharedPreferences editor = mContext.getSharedPreferences(
+                OverlaySettingsPreferenceController.SHARE_PERFS,
+                Context.MODE_PRIVATE);
+        editor.edit().putBoolean(OverlaySettingsPreferenceController.SHARE_PERFS, false).apply();
+
+        assertThat(
+                OverlaySettingsPreferenceController.isOverlaySettingsEnabled(mContext)).isFalse();
+    }
+
+    @Test
+    public void setOverlaySettingsEnabled_setTrue_shouldStoreTrue() {
+        OverlaySettingsPreferenceController.setOverlaySettingsEnabled(mContext, true);
+
+        assertThat(
+                OverlaySettingsPreferenceController.isOverlaySettingsEnabled(mContext)).isTrue();
+    }
+
+    @Test
+    public void setOverlaySettingsEnabled_setFalse_shouldStoreTrue() {
+        OverlaySettingsPreferenceController.setOverlaySettingsEnabled(mContext, false);
+
+        assertThat(
+                OverlaySettingsPreferenceController.isOverlaySettingsEnabled(mContext)).isFalse();
+    }
+}