Marking CarInputManager methods with SystemApi

Test: atest CarServiceUnitTest
Bug: 159623196
Change-Id: I27e07b691167853000632db3c42324b8c855979c
diff --git a/service/AndroidManifest.xml b/service/AndroidManifest.xml
index 1fe8c0c..e9755a5 100644
--- a/service/AndroidManifest.xml
+++ b/service/AndroidManifest.xml
@@ -780,6 +780,13 @@
          android:label="@string/car_permission_label_set_car_vendor_category_10"
          android:description="@string/car_permission_desc_set_car_vendor_category_10"/>
 
+    <!-- Allows an application to receive Car input events.
+        <p>Protection level: signature
+    -->
+    <permission android:name="android.car.permission.CAR_MONITOR_INPUT"
+                android:protectionLevel="signature"
+                android:label="@string/car_permission_label_monitor_input"
+                android:description="@string/car_permission_desc_monitor_input"/>
 
     <uses-permission android:name="android.permission.CALL_PHONE"/>
     <uses-permission android:name="android.permission.DEVICE_POWER"/>