Add dark theme custom type into the dark theme settings page

Also fix some test cases.

I'd prefer using Robolectric shadows rather than mocking Android
framework classes. However, I can't do that in this CL due to the
lack of multiple shadow classes support.

Test: make RunSettingsRoboTests -j56
      ROBOTEST_FILTER=com.android.settings.display.darkmode.*
Bug: 215182463
Change-Id: If557d2933927a5dd0fadd3f6db6bb6f0ab7dd5ee

src/com/android/settings/display/darkmode/BedtimeSettings.java

@@ -0,0 +1,60 @@
+/*
+ * Copyright (C) 2022 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.display.darkmode;
+
+import android.content.Context;
+import android.content.Intent;
+import android.content.pm.PackageManager;
+import android.content.pm.ResolveInfo;
+
+import androidx.annotation.Nullable;
+import androidx.annotation.VisibleForTesting;
+
+/** Manages Digital Wellbeing bedtime settings' intents. */
+public final class BedtimeSettings {
+    @VisibleForTesting
+    public static final String ACTION_BEDTIME_SETTINGS = "android.settings.BEDTIME_SETTINGS";
+
+    private final Context mContext;
+    private final PackageManager mPackageManager;
+    private final String mWellbeingPackage;
+
+    public BedtimeSettings(Context context) {
+        mContext = context;
+        mPackageManager = context.getPackageManager();
+        mWellbeingPackage = mContext.getResources().getString(
+                com.android.internal.R.string.config_defaultWellbeingPackage);
+    }
+
+    /**
+     * Returns the bedtime settings intent. If the bedtime settings isn't available, returns
+     * {@code null}.
+     */
+    @Nullable
+    public Intent getBedtimeSettingsIntent() {
+        Intent bedtimeSettingsIntent = new Intent(ACTION_BEDTIME_SETTINGS).setPackage(
+                mWellbeingPackage);
+        ResolveInfo bedtimeSettingInfo = mPackageManager.resolveActivity(bedtimeSettingsIntent,
+                PackageManager.MATCH_DEFAULT_ONLY);
+
+        if (bedtimeSettingInfo != null && bedtimeSettingInfo.activityInfo.isEnabled()) {
+            return bedtimeSettingsIntent;
+        } else {
+            return null;
+        }
+    }
+}