Add a developer option to allow all background activity starts

Test: make RunSettingsRoboTests ROBOTEST_FILTER=AllowBackgroundActivityStartsPreferenceControllerTest
Bug: 110956953
Change-Id: I45db536d8a60aa6c3a81c01b93ff8e13bf52a77b

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

@@ -0,0 +1,68 @@
+/*
+ * Copyright (C) 2018 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.provider.Settings;
+
+import com.android.settings.core.PreferenceControllerMixin;
+import com.android.settingslib.development.DeveloperOptionsPreferenceController;
+
+import androidx.preference.Preference;
+import androidx.preference.SwitchPreference;
+
+public class AllowBackgroundActivityStartsPreferenceController
+        extends DeveloperOptionsPreferenceController
+        implements Preference.OnPreferenceChangeListener, PreferenceControllerMixin {
+
+    private static final String BACKGROUND_ACTIVITY_STARTS_ENABLED_KEY
+            = "allow_background_activity_starts";
+
+    public AllowBackgroundActivityStartsPreferenceController(Context context) {
+        super(context);
+    }
+
+    @Override
+    public String getPreferenceKey() {
+        return BACKGROUND_ACTIVITY_STARTS_ENABLED_KEY;
+    }
+
+    @Override
+    public boolean onPreferenceChange(Preference preference, Object newValue) {
+        writeSetting((boolean) newValue);
+        return true;
+    }
+
+    private void writeSetting(boolean isEnabled) {
+        Settings.Global.putInt(mContext.getContentResolver(),
+                Settings.Global.BACKGROUND_ACTIVITY_STARTS_ENABLED, isEnabled ? 1 : 0);
+    }
+
+    @Override
+    public void updateState(Preference preference) {
+        final int mode = Settings.Global.getInt(mContext.getContentResolver(),
+                Settings.Global.BACKGROUND_ACTIVITY_STARTS_ENABLED, 1);
+        ((SwitchPreference) mPreference).setChecked(mode != 0);
+    }
+
+    @Override
+    protected void onDeveloperOptionsSwitchDisabled() {
+        super.onDeveloperOptionsSwitchDisabled();
+        writeSetting(false);
+        ((SwitchPreference) mPreference).setChecked(false);
+    }
+}