Add accessibility service description

lawnchair/AndroidManifest.xml

@@ -99,6 +99,9 @@
             <intent-filter>
                 <action android:name="android.accessibilityservice.AccessibilityService" />
             </intent-filter>
+            <meta-data
+                android:name="android.accessibilityservice"
+                android:resource="@xml/accessibility_service_config" />
         </service>
 
         <provider

lawnchair/res/values/strings.xml

@@ -565,4 +565,5 @@
     <string name="search_algorithm_global_search_via_asi">Global Search (via ASI)</string>
     <string name="app_search_algorithm">Search Algorithm</string>
     <string name="all_apps_search_result_calculator">Calculator</string>
+    <string name="accessibility_service_description">To lock your phone when performing a gesture, Lawnchair requires accessibility access.\n\nLawnchair doesn\'t watch any user action, though the privilege to do so is required for all accessibility services. Lawnchair discards any event sent by the system.\n\nIn order to lock your phone, Lawnchair uses the performGlobalAction Accessibility service.</string>
 </resources>

res/xml/accessibility_service_config.xml

@@ -0,0 +1,5 @@
+<?xml version="1.0" encoding="utf-8"?>
+<accessibility-service xmlns:android="http://schemas.android.com/apk/res/android"
+    android:description="@string/accessibility_service_description"
+    android:packageNames=""
+    />