Add settings for scheduling dark theme

Adding a settings page similar to night light for Dark theme. it will allow the user to schedule
dark mode from sunrise to sunset

Test: make -j64 RunSettingsRoboTests ROBOTEST_FILTER="com.android.settings.display.DarkUIPreferenceControllerTest" && \
make -j64 RunSettingsRoboTests ROBOTEST_FILTER="com.android.settings.display.darkmode.DarkModeActivationPreferenceControllerTest" && \
make -j64 RunSettingsRoboTests ROBOTEST_FILTER="com.android.settings.display.darkmode.DarkModeObserverTest" && \
make -j64 RunSettingsRoboTests ROBOTEST_FILTER="com.android.settings.display.darkmode.DarkModeScheduleSelectorControllerTest"

Fixes: 141567787

Change-Id: I3094b655c04f59c23a95162a1be5ee8260e28a48

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

@@ -0,0 +1,81 @@
+/*
+ * Copyright (C) 2019 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.os.Bundle;
+import android.app.settings.SettingsEnums;
+import com.android.settings.R;
+import com.android.settings.dashboard.DashboardFragment;
+import com.android.settings.search.BaseSearchIndexProvider;
+import com.android.settingslib.search.SearchIndexable;
+
+/**
+ * Settings screen for Dark UI Mode
+ */
+@SearchIndexable(forTarget = SearchIndexable.ALL & ~SearchIndexable.ARC)
+public class DarkModeSettingsFragment extends DashboardFragment {
+
+    private static final String TAG = "DarkModeSettingsFragment";
+    private DarkModeObserver mContentObserver;
+    private Runnable mCallback = () -> {
+        updatePreferenceStates();
+    };
+
+    @Override
+    public void onCreate(Bundle savedInstanceState) {
+        super.onCreate(savedInstanceState);
+
+        final Context context = getContext();
+        mContentObserver = new DarkModeObserver(context);
+    }
+
+    @Override
+    public void onStart() {
+        super.onStart();
+        // Listen for changes only while visible.
+        mContentObserver.subscribe(mCallback);
+    }
+
+    @Override
+    public void onStop() {
+        super.onStop();
+        // Stop listening for state changes.
+        mContentObserver.unsubscribe();
+    }
+
+    @Override
+    protected int getPreferenceScreenResId() {
+        return R.xml.dark_mode_settings;
+    }
+
+    @Override
+    public int getHelpResource() {
+        return R.string.help_url_dark_theme;
+    }
+
+    @Override
+    protected String getLogTag() {
+        return TAG;
+    }
+
+    @Override
+    public int getMetricsCategory() {
+        return SettingsEnums.DARK_UI_SETTINGS;
+    }
+
+    public static final BaseSearchIndexProvider SEARCH_INDEX_DATA_PROVIDER =
+            new BaseSearchIndexProvider(R.xml.dark_mode_settings);
+}