Separate "Keyboard" from "Language & input"

1. Separate "Keyboard" from "Language & input".
2. Use FeatureFlagUtils.SETTINGS_NEW_KEYBOARD_UI to control the
   different UI until Settings launches the new UI design.

Bug: 242680328
Test: local test
Change-Id: Id1ea6d3e3c2e6b83bc4b4d835c6b27e31311c530

src/com/android/settings/inputmethod/KeyboardPreferenceController.java

@@ -0,0 +1,95 @@
+/*
+ * Copyright (C) 2022 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.inputmethod;
+
+import android.content.Context;
+import android.hardware.input.InputManager;
+import android.util.FeatureFlagUtils;
+
+import androidx.preference.Preference;
+
+import com.android.settings.R;
+import com.android.settings.core.BasePreferenceController;
+import com.android.settings.core.PreferenceControllerMixin;
+import com.android.settings.inputmethod.PhysicalKeyboardFragment.HardKeyboardDeviceInfo;
+import com.android.settingslib.core.lifecycle.LifecycleObserver;
+import com.android.settingslib.core.lifecycle.events.OnPause;
+import com.android.settingslib.core.lifecycle.events.OnResume;
+
+import java.util.List;
+
+public class KeyboardPreferenceController extends BasePreferenceController
+        implements PreferenceControllerMixin, LifecycleObserver, OnResume, OnPause,
+        InputManager.InputDeviceListener {
+
+    private final InputManager mIm;
+
+    private Preference mPreference;
+
+    public KeyboardPreferenceController(Context context, String key) {
+        super(context, key);
+        mIm = context.getSystemService(InputManager.class);
+    }
+
+    @Override
+    public void onInputDeviceAdded(int deviceId) {
+        updateSummary();
+    }
+
+    @Override
+    public void onInputDeviceRemoved(int deviceId) {
+        updateSummary();
+    }
+
+    @Override
+    public void onInputDeviceChanged(int deviceId) {
+        updateSummary();
+    }
+
+    @Override
+    public void onPause() {
+        mIm.unregisterInputDeviceListener(this);
+    }
+
+    @Override
+    public void onResume() {
+        mIm.registerInputDeviceListener(this, null);
+    }
+
+    @Override
+    public void updateState(Preference preference) {
+        mPreference = preference;
+        updateSummary();
+    }
+
+    @Override
+    public int getAvailabilityStatus() {
+        boolean isFeatureOn = FeatureFlagUtils
+                .isEnabled(mContext, FeatureFlagUtils.SETTINGS_NEW_KEYBOARD_UI);
+        return isFeatureOn ? AVAILABLE : CONDITIONALLY_UNAVAILABLE;
+    }
+
+    private void updateSummary() {
+        final List<HardKeyboardDeviceInfo> keyboards =
+                PhysicalKeyboardFragment.getHardKeyboards(mContext);
+        if (keyboards.isEmpty()) {
+            mPreference.setSummary(R.string.keyboard_settings_summary);
+        } else {
+            mPreference.setSummary(R.string.keyboard_settings_with_physical_keyboard_summary);
+        }
+    }
+}