Reorganize notification Settings classes

The notification package was getting too big.

Test: make -j64 RunSettingsRoboTests
Fixes: 145224451
Change-Id: I25ba82f42f7a137d8adcce72dcf8089d0e018bdc

src/com/android/settings/notification/app/DescriptionPreferenceController.java

@@ -0,0 +1,68 @@
+/*
+ * Copyright (C) 2017 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.notification.app;
+
+import android.content.Context;
+import android.text.TextUtils;
+
+import androidx.preference.Preference;
+
+import com.android.settings.core.PreferenceControllerMixin;
+
+public class DescriptionPreferenceController extends NotificationPreferenceController
+        implements PreferenceControllerMixin {
+
+    private static final String KEY_DESC = "desc";
+
+    public DescriptionPreferenceController(Context context) {
+        super(context, null);
+    }
+
+    @Override
+    public String getPreferenceKey() {
+        return KEY_DESC;
+    }
+
+    @Override
+    public boolean isAvailable() {
+        if (!super.isAvailable()) {
+            return false;
+        }
+        if (mChannel == null && !hasValidGroup()) {
+            return false;
+        }
+        if (mChannel != null && !TextUtils.isEmpty(mChannel.getDescription())) {
+            return true;
+        }
+        if (hasValidGroup() && !TextUtils.isEmpty(mChannelGroup.getDescription())) {
+            return true;
+        }
+        return false;
+    }
+
+    public void updateState(Preference preference) {
+        if (mAppRow != null) {
+            if (mChannel != null) {
+                preference.setTitle(mChannel.getDescription());
+            } else if (hasValidGroup()) {
+                preference.setTitle(mChannelGroup.getDescription());
+            }
+        }
+        preference.setEnabled(false);
+        preference.setSelectable(false);
+    }
+}