Add flow for updating zen mode status on modes pages

The main responsibility for updating stored ZenMode data when updated is the Settings page, which reloads mode data whenever any changes are detected. This change adds a process for that Settings page to then update the ZenMode data associated with all controllers on that page.

Flag: android.app.modes_ui
Bug: 335259054
Test: manual with toy implementations
Change-Id: Ie1692da54d962c90378085d8bd8573e5b93f8eb6

src/com/android/settings/notification/modes/AbstractZenModePreferenceController.java

@@ -0,0 +1,80 @@
+/*
+ * Copyright (C) 2024 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.modes;
+
+import android.app.AutomaticZenRule;
+import android.content.Context;
+
+import androidx.annotation.NonNull;
+import androidx.annotation.Nullable;
+import androidx.preference.Preference;
+
+import com.android.settingslib.core.AbstractPreferenceController;
+
+/**
+ * Base class for any preference controllers pertaining to any single Zen mode.
+ */
+abstract class AbstractZenModePreferenceController extends AbstractPreferenceController {
+
+    @Nullable
+    protected ZenModesBackend mBackend;
+
+    @Nullable  // only until updateZenMode() is called
+    private ZenMode mZenMode;
+
+    @NonNull
+    final String mKey;
+
+    // ZenModesBackend should only be passed in if the preference controller may set the user's
+    // policy for this zen mode. Otherwise, if the preference controller is essentially read-only
+    // and leads to a further Settings screen, backend should be null.
+    AbstractZenModePreferenceController(@NonNull Context context, @NonNull String key,
+            @Nullable ZenModesBackend backend) {
+        super(context);
+        mBackend = backend;
+        mKey = key;
+    }
+
+    @Override
+    @NonNull
+    public String getPreferenceKey() {
+        return mKey;
+    }
+
+    // Called by the parent Fragment onStart, which means it will happen before resume.
+    public void updateZenMode(@NonNull Preference preference, @NonNull ZenMode zenMode) {
+        mZenMode = zenMode;
+        updateState(preference);
+    }
+
+    @Nullable
+    public ZenMode getMode() {
+        return mZenMode;
+    }
+
+    @Nullable
+    public AutomaticZenRule getAZR() {
+        if (mZenMode == null || mZenMode.getRule() == null) {
+            return null;
+        }
+        return mZenMode.getRule();
+    }
+
+    /** Implementations of this class should override
+     *  {@link AbstractPreferenceController#updateState(Preference)} to specify what should
+     *  happen when the preference is updated */
+}