Add Live Caption preference to Accessibility page.

This reverts commit fa27a88292.

The original was only a temporary revert in order to remove from initial beta release for dogfooding before the feature was ready.

Reason for revert: b/123652115

Bug:123652115
Test: manual
Change-Id: Id647c2992e30289d72a4f6144829a997677be3fa

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

@@ -0,0 +1,58 @@
+/*
+ * Copyright (C) 2019 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.content.Context;
+import android.content.Intent;
+import android.content.pm.PackageManager;
+import android.content.pm.ResolveInfo;
+
+import androidx.annotation.VisibleForTesting;
+import androidx.preference.Preference;
+
+import com.android.settings.core.BasePreferenceController;
+
+import java.util.List;
+
+public class LiveCaptionPreferenceController extends BasePreferenceController {
+
+    @VisibleForTesting
+    static final Intent LIVE_CAPTION_INTENT = new Intent(
+            "com.android.settings.action.live_caption");
+
+    private final PackageManager mPackageManager;
+
+    public LiveCaptionPreferenceController(Context context, String preferenceKey) {
+        super(context, preferenceKey);
+        mPackageManager = context.getPackageManager();
+    }
+
+    @Override
+    public int getAvailabilityStatus() {
+        final List<ResolveInfo> resolved =
+                mPackageManager.queryIntentActivities(LIVE_CAPTION_INTENT, 0 /* flags */);
+        return resolved != null && !resolved.isEmpty()
+                ? AVAILABLE
+                : UNSUPPORTED_ON_DEVICE;
+    }
+
+    @Override
+    public void updateState(Preference preference) {
+        super.updateState(preference);
+        preference.setIntent(LIVE_CAPTION_INTENT);
+    }
+}