Add TelephonyMonitor debug switch in Developer Options.

Test: make ROBOTEST_FILTER=TelephonyMonitorPreferenceControllerTest
RunSettingsRoboTests -j40

Bug:35206589
Change-Id: I72d89acab95980511a2fd54420fd9d3c5ddaddab

src/com/android/settings/development/TelephonyMonitorPreferenceController.java

@@ -0,0 +1,95 @@
+/*
+ * Copyright (C) 2017 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.development;
+
+import android.content.Context;
+import android.os.SystemProperties;
+import android.support.v14.preference.SwitchPreference;
+import android.support.v7.preference.Preference;
+import android.support.v7.preference.PreferenceScreen;
+import android.widget.Toast;
+
+import com.android.settings.core.PreferenceController;
+import com.android.settings.R;
+
+public class TelephonyMonitorPreferenceController extends PreferenceController {
+
+    private static final String KEY_TELEPHONY_MONITOR_SWITCH = "telephony_monitor_switch";
+    static final String BUILD_TYPE = "ro.build.type";
+    static final String PROPERTY_TELEPHONY_MONITOR = "persist.radio.enable_tel_mon";
+
+    private SwitchPreference mPreference;
+
+    public TelephonyMonitorPreferenceController(Context context) {
+        super(context);
+    }
+
+    @Override
+    public void displayPreference(PreferenceScreen screen) {
+        super.displayPreference(screen);
+        if (isAvailable()) {
+            mPreference = (SwitchPreference) screen.findPreference(KEY_TELEPHONY_MONITOR_SWITCH);
+            mPreference.setChecked(SystemProperties.getBoolean(PROPERTY_TELEPHONY_MONITOR, false));
+        }
+    }
+
+    @Override
+    public String getPreferenceKey() {
+        return KEY_TELEPHONY_MONITOR_SWITCH;
+    }
+
+    @Override
+    public boolean isAvailable() {
+        return mContext.getResources().getBoolean(R.bool.config_show_telephony_monitor) &&
+                (SystemProperties.get(BUILD_TYPE).equals("userdebug") ||
+                        SystemProperties.get(BUILD_TYPE).equals("eng"));
+    }
+
+    @Override
+    public void updateState(Preference preference) {
+        updatePreference();
+    }
+
+    @Override
+    public boolean handlePreferenceTreeClick(Preference preference) {
+        if (KEY_TELEPHONY_MONITOR_SWITCH.equals(preference.getKey())) {
+            final SwitchPreference switchPreference = (SwitchPreference) preference;
+            SystemProperties.set(PROPERTY_TELEPHONY_MONITOR,
+                    switchPreference.isChecked() ? "true" : "false");
+            Toast.makeText(mContext, R.string.telephony_monitor_toast,
+                    Toast.LENGTH_LONG).show();
+            return true;
+        }
+        return false;
+    }
+
+    public void enablePreference(boolean enabled) {
+        if (isAvailable()) {
+            mPreference.setEnabled(enabled);
+        }
+    }
+
+    public boolean updatePreference() {
+        if (!isAvailable()) {
+            return false;
+        }
+        final boolean enabled = SystemProperties.getBoolean(PROPERTY_TELEPHONY_MONITOR, false);
+        mPreference.setChecked(enabled);
+        return enabled;
+    }
+
+}