Add audio adjustment fragment in a11y settings

Accessibility settings audio and on-screen text category restructure,
add audio adjustment fragment for related accessibility services.

Bug: 174829936
Test: atest AudioAdjustmentFragmentTest, atest AccessibilitySettingsTest
Change-Id: I8b4397d042a0e7ce1242f95319a6a25cc45f38bb

src/com/android/settings/accessibility/AudioAdjustmentFragment.java

@@ -0,0 +1,50 @@
+/*
+ * Copyright (C) 2021 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.accessibility;
+
+import android.app.settings.SettingsEnums;
+
+import com.android.settings.R;
+import com.android.settings.dashboard.DashboardFragment;
+import com.android.settings.search.BaseSearchIndexProvider;
+import com.android.settingslib.search.SearchIndexable;
+
+/** Accessibility settings for audio adjustment. */
+@SearchIndexable(forTarget = SearchIndexable.ALL & ~SearchIndexable.ARC)
+public class AudioAdjustmentFragment extends DashboardFragment {
+
+    private static final String TAG = "AudioAdjustmentFragment";
+
+    @Override
+    public int getMetricsCategory() {
+        return SettingsEnums.ACCESSIBILITY_AUDIO_ADJUSTMENT;
+    }
+
+    @Override
+    protected int getPreferenceScreenResId() {
+        return R.xml.accessibility_audio_adjustment;
+    }
+
+    @Override
+    protected String getLogTag() {
+        return TAG;
+    }
+
+    public static final BaseSearchIndexProvider SEARCH_INDEX_DATA_PROVIDER =
+            new BaseSearchIndexProvider(R.xml.accessibility_audio_adjustment);
+
+}