Update design of channel pages.

Test: atest
Bug: 127796543
Change-Id: I4fabeafe2602c341554959303e67bc69c8817a8f

src/com/android/settings/notification/MinImportancePreferenceController.java

@@ -0,0 +1,84 @@
+/*
+ * 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;
+
+import static android.app.NotificationManager.IMPORTANCE_LOW;
+import static android.app.NotificationManager.IMPORTANCE_MIN;
+
+import android.app.NotificationChannel;
+import android.content.Context;
+
+import com.android.settings.core.PreferenceControllerMixin;
+import com.android.settingslib.RestrictedSwitchPreference;
+
+import androidx.preference.Preference;
+
+public class MinImportancePreferenceController extends NotificationPreferenceController
+        implements PreferenceControllerMixin, Preference.OnPreferenceChangeListener  {
+
+    private static final String KEY_IMPORTANCE = "min_importance";
+    private NotificationSettingsBase.ImportanceListener mImportanceListener;
+
+    public MinImportancePreferenceController(Context context,
+            NotificationSettingsBase.ImportanceListener importanceListener,
+            NotificationBackend backend) {
+        super(context, backend);
+        mImportanceListener = importanceListener;
+    }
+
+    @Override
+    public String getPreferenceKey() {
+        return KEY_IMPORTANCE;
+    }
+
+    @Override
+    public boolean isAvailable() {
+        if (!super.isAvailable()) {
+            return false;
+        }
+        if (mChannel == null) {
+            return false;
+        }
+        if (isDefaultChannel()) {
+            return false;
+        }
+        return mChannel.getImportance() <= IMPORTANCE_LOW;
+    }
+
+    @Override
+    public void updateState(Preference preference) {
+        if (mAppRow!= null && mChannel != null) {
+            preference.setEnabled(mAdmin == null && isChannelConfigurable());
+
+            RestrictedSwitchPreference pref = (RestrictedSwitchPreference) preference;
+            pref.setChecked(mChannel.getImportance() == IMPORTANCE_MIN);
+        }
+    }
+
+    @Override
+    public boolean onPreferenceChange(Preference preference, Object newValue) {
+        if (mChannel != null) {
+            final boolean checked = (boolean) newValue;
+
+            mChannel.setImportance(checked ? IMPORTANCE_MIN : IMPORTANCE_LOW);
+            mChannel.lockFields(NotificationChannel.USER_LOCKED_IMPORTANCE);
+            saveChannel();
+            mImportanceListener.onImportanceChanged();
+        }
+        return true;
+    }
+}