Refactor IMEAndLanguageSettings to use PreferenceController

Bug: 32642706
Bug: 32637613
Bug: 32643833
Test: RunSettingsRoboTests

This change is necessary to test preference controlling logic, as well
as making preferences reusable in other Preference pages in the new
information architecture.

Change-Id: I9e2fd2f6800579f005a5c303ed03ae06477006a6

src/com/android/settings/language/TtsPreferenceController.java

@@ -0,0 +1,60 @@
+/*
+ * Copyright (C) 2016 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.language;
+
+import android.content.Context;
+import android.speech.tts.TtsEngines;
+import android.support.v7.preference.Preference;
+import android.support.v7.preference.PreferenceScreen;
+
+import com.android.settings.core.PreferenceController;
+
+public class TtsPreferenceController extends PreferenceController {
+
+    private static final String KEY_VOICE_CATEGORY = "voice_category";
+    private static final String KEY_TTS_SETTINGS = "tts_settings";
+
+    private final TtsEngines mTtsEngines;
+
+    public TtsPreferenceController(Context context, TtsEngines ttsEngines) {
+        super(context);
+        mTtsEngines = ttsEngines;
+    }
+
+    @Override
+    public boolean isAvailable() {
+        return !mTtsEngines.getEngines().isEmpty();
+    }
+
+    @Override
+    public void displayPreference(PreferenceScreen screen) {
+        super.displayPreference(screen);
+        if (!isAvailable()) {
+            removePreference(screen, KEY_VOICE_CATEGORY);
+        }
+    }
+
+    @Override
+    public boolean handlePreferenceTreeClick(Preference preference) {
+        return false;
+    }
+
+    @Override
+    public String getPreferenceKey() {
+        return KEY_TTS_SETTINGS;
+    }
+}