Improve lifecycle of ZenModeFragment & friends

* Don't keep Settings observers longer than start-stop.
* Only call updateState() once on controllers during create->start->resume.
* Remove some duplicate controller update methods from ZenModesFragmentBase (we can directly call DashboardFragment's).
* Don't update controllers if unrelated modes were changed.
* Extract ZenSettingsObserver for use in the link tile later.
* Add tests.

Fixes: 353946788
Test: atest com.android.settings.notification.modes
Flag: android.app.modes_ui
Change-Id: I64b51714d699b5c3a592a76fcb615d2999998829

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

@@ -0,0 +1,68 @@
+/*
+ * 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.content.Context;
+import android.database.ContentObserver;
+import android.net.Uri;
+import android.provider.Settings;
+
+import androidx.annotation.Nullable;
+
+class ZenSettingsObserver extends ContentObserver {
+    private static final Uri ZEN_MODE_URI = Settings.Global.getUriFor(Settings.Global.ZEN_MODE);
+    private static final Uri ZEN_MODE_CONFIG_ETAG_URI = Settings.Global.getUriFor(
+            Settings.Global.ZEN_MODE_CONFIG_ETAG);
+
+    private final Context mContext;
+    @Nullable private Runnable mCallback;
+
+    ZenSettingsObserver(Context context) {
+        this(context, null);
+    }
+
+    ZenSettingsObserver(Context context, @Nullable Runnable callback) {
+        super(context.getMainExecutor(), 0);
+        mContext = context;
+        setOnChangeListener(callback);
+    }
+
+    void register() {
+        mContext.getContentResolver().registerContentObserver(ZEN_MODE_URI, false, this);
+        mContext.getContentResolver().registerContentObserver(ZEN_MODE_CONFIG_ETAG_URI, false,
+                this);
+    }
+
+    void unregister() {
+        mContext.getContentResolver().unregisterContentObserver(this);
+    }
+
+    void setOnChangeListener(@Nullable Runnable callback) {
+        mCallback = callback;
+    }
+
+    @Override
+    public void onChange(boolean selfChange, @Nullable Uri uri) {
+        super.onChange(selfChange, uri);
+        // Shouldn't have any other URIs trigger this method, but check just in case.
+        if (ZEN_MODE_URI.equals(uri) || ZEN_MODE_CONFIG_ETAG_URI.equals(uri)) {
+            if (mCallback != null) {
+                mCallback.run();
+            }
+        }
+    }
+}