Change dark theme screen to toggle

The dark theme screen has been removed in favor of a simple
toggle with a dialog that shows up the first time a user
tries to enable dark theme when in light theme.

Test: robotests pass
Bug: 130251804
Change-Id: I48f8e24a2b2a117e5a8054c5bc0b240ba68fe1ad

src/com/android/settings/display/DarkUIInfoDialogFragment.java

@@ -0,0 +1,93 @@
+/*
+ * 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;
+
+import static com.android.settings.display.DarkUIPreferenceController.DARK_MODE_PREFS;
+import static com.android.settings.display.DarkUIPreferenceController.PREF_DARK_MODE_DIALOG_SEEN;
+
+import android.app.Dialog;
+import android.app.UiModeManager;
+import android.content.Context;
+import android.content.DialogInterface;
+import android.os.Bundle;
+import android.provider.Settings;
+import android.view.LayoutInflater;
+import android.view.View;
+import android.widget.ImageView;
+import android.widget.TextView;
+
+import androidx.annotation.NonNull;
+import androidx.annotation.Nullable;
+import androidx.appcompat.app.AlertDialog;
+
+import com.android.settings.R;
+import com.android.settings.core.instrumentation.InstrumentedDialogFragment;
+
+public class DarkUIInfoDialogFragment extends InstrumentedDialogFragment
+        implements DialogInterface.OnClickListener{
+
+    @Override
+    public int getMetricsCategory() {
+        // TODO(b/130251804): Add metrics constant in followup change to avoid merge conflict in
+        // beta cherrypick
+        return 0;
+    }
+
+    @NonNull
+    @Override
+    public Dialog onCreateDialog(@Nullable Bundle savedInstanceState) {
+        Context context = getContext();
+        AlertDialog.Builder dialog = new AlertDialog.Builder(context);
+        LayoutInflater inflater = LayoutInflater.from(dialog.getContext());
+        View titleView = inflater.inflate(R.layout.settings_dialog_title, null);
+        ((ImageView) titleView.findViewById(R.id.settings_icon))
+                .setImageDrawable(context.getDrawable(R.drawable.dark_theme));
+        ((TextView) titleView.findViewById(R.id.settings_title)).setText(R.string.dark_ui_mode);
+
+        dialog.setCustomTitle(titleView)
+                .setMessage(R.string.dark_ui_settings_dark_summary)
+                .setPositiveButton(
+                        R.string.dark_ui_settings_dialog_acknowledge,
+                        this);
+        return dialog.create();
+    }
+
+    @Override
+    public void onDismiss(@NonNull DialogInterface dialog) {
+        enableDarkTheme();
+        super.onDismiss(dialog);
+    }
+
+    @Override
+    public void onClick(DialogInterface dialogInterface, int i) {
+        // We have to manually dismiss the dialog because changing night mode causes it to
+        // recreate itself.
+        dialogInterface.dismiss();
+        enableDarkTheme();
+    }
+
+    private void enableDarkTheme() {
+        final Context context = getContext();
+        if (context != null) {
+            Settings.Secure.putInt(context.getContentResolver(),
+                    Settings.Secure.DARK_MODE_DIALOG_SEEN,
+                    DarkUIPreferenceController.DIALOG_SEEN);
+            context.getSystemService(UiModeManager.class)
+                    .setNightMode(UiModeManager.MODE_NIGHT_YES);
+        }
+    }
+}